I'm a retired civil engineer. Travelled quite a bit ..... even been to Canada a few times ..... but only BC and Alberta. My family are not fish keeping enthusiasts ... but they're happy I have something to keep me out of trouble .... also they're somewhat amused that I have a KZfaq channel in my old age.

Hi. I'm told that these days the large 100 yen stores in Japan have so many varieties and types of stuff for sale that it can be quite overwhelming. Some years since I was in Japan but at that time I was not interested in medaka.

Just found your channel and I've subscribed. I'm thinking of getting some medaka for outside. Where did you source your original fish from?

I always forget to count .......... but I'm sure I've produced more than enough. However I'll have to wait until September to see how many survive the very hot and rainy summer weather.

@@fsr170409 Hi. There are none in any local fish stores but I managed to find a source on Facebook willing to let me have some. Had to drive quite a way to collect them and they are not pure bred strains. However they are reasonably colorful and I'm happy with that.

Sub tropical climate? So you're not in the UK then.

@@StuartChignell Hi. No, not the UK .....I'm in Asia. But a friend sent me this link about UK retailers only selling medaka for indoor aquariums and to ensure customers understand they cannot be kept in outdoor ponds or barrels ornamentalfish.org/industry-warned-to-ensure-oryzias-species-must-only-be-sold-for-indoor-aquariums/ . Presumably it's not illegal to keep medaka outdoors in the UK ... it appears to be just an advisory warning that government may in future ban the import of live medaka if they become an invasive risk due to being kept outdoors.

Hi, I'm in Asia in a sub-tropical climate. To produce eggs like that, your medaka must be happy and healthy in the environment you've provided for them, Looks like in a month's time you may have collected 600 eggs.

@@km-qh3rs aaaahhhh I was hoping you were in the UK like me. Now watching all your videos 😂 I have established tubs outside with 3 different types of Medaka so far. I do have plants including Lily’s and use the same spawning mops as you although use the pool noodle idea. Definitely very addictive and extremely rewarding.

I tend to doubt that liquid fertilizer makes much difference. However fertilizer spikes always seem very expensive to me ...... so I sometimes wrap granular plant fertilizer in some cotton material and bury that in the water lily pot. The idea is that the cotton material will prevent the granules from dissolving too quickly. Not sure if it's a good idea or not but no water lilies have died yet. I regret I don't sell medaka fish or eggs. I couldn't handle the logistics of that and anyway I think people would probably be disappointed with the quality of the fish because my medaka are not pure bred strains.

I put the spawning mop in a 10 liter bucket of water. In about 3 weeks I'll probably tip the water into the pond to give any hatched fry a chance.

Thanks. I'm somewhat elderly and running the channel helps keep my brain active. Always happy to answer questions although sometimes there may be a few days delay.

About 9 to 10 gallons. I've only ever kept medaka in a sub-tropical climate so I'm not really qualified to advise about keeping medaka in a clay pot in your area in -17degC conditions. However I think clay pots are slightly porous and the water in the pores may expand when it turns to ice and the pot may crack. Also my guess would be that there's a high risk of the medaka not surviving outdoors if -17degC temperatures continue for a long period of time. But that's only my guess. Reddit has online an r/medaka community who are usually helpful answering any similar questions you might have.

Hi, depends on how much you want to pay? I think you may find something similar at about US$10 incl. int. shipping on ebay if you search maybe "fish photo observation watching tank box". Not sure if they ship to Canada. I don't know if you're aware that amazon.jp.co has an English version of its website. Search for medaka etc and it will produce lots of results ... e.g. medaka for sale in Japan (do not ship overseas but shows prices in Japan) ...... other medaka related stuff, some of which may be shipped overseas but shipping costs maybe about US$25.

A capacity of 35 to 40 liters ... about 9 to 10 gallons.

I only ever feed powdered fry food ... something similar to Hikari First Bites which I think you can get in the UK ..... feed 3 or more times a day. If the newly hatched fry are healthy and strong enough I've found they have no problems eating that within 1 or 2 days of hatching. I would have thought that feeding liquifry risks severely polluting the water. Fry are very fragile for the first 2 weeks. So, ideally, there would be no water changes for 2 weeks ..... however I may do a 20% water change at the end of the first week ..... but it's essential to do this by using a slow drip method. I wouldn't worry ..... medaka fry at 2 weeks old are still very small and it's not unusual if some have a slower growth than others ..... as long as the fry are swimming about they should be OK. Note that where the parents are juveniles, the females tend to produce smaller eggs than fully adult fish and consequently the fry may be initially smaller.

@@km-qh3rs hi thank you very much for the great advise. Much obliged

@@km-qh3rs Interesting that you do not recommend water changes generally. What about the growth stunting hormones fry are said to release? Thanks for the advice re liquifry

@@H.Ali_08 Maybe I haven't been sufficiently clear ..... as above " Fry are very fragile for the first 2 weeks. So, ideally, there would be no water changes for 2 weeks ..... however I may do a 20% water change at the end of the first week" ..... so I'm only talking about the first 2 weeks and have never suggested that water changes are generally not recommended. In fact, if you listen from minute 8.30 onwards in my above "water changes" video you will note that, for newly hatched fry, after the first 2 weeks I usually make a 20% water change either every day or every 2 days. Also I'll add that I don't believe in growth stunting hormones. As far as I'm aware, no-one has been able to identify chemically exactly what type of hormone it might be. But there may be metabolic change chemicals in water containing large numbers of fish which may restrict growth rate. However, as with all animals, some fish are stronger than others and can reduce any deleterious effects of these chemicals.

@@km-qh3rs Thanks that is very clear. Interesting to know. Despite not getting any eggs at first, I am now inundated since I purchased a heater for the indoor tank. I have a mesh box inside my tank wherein I have placed the eggs to ensure that the eggs stay in 25 c consistently to enable them to hatch sooner. I have also placed plants like hornwort, dwarf water lettuce and water cress within that fine mesh box. This enables the Medaka outside of the mesh box but in the tank to lay eggs on the homemade egg-laying item. I am keeping my two two-week old fry that I had purchased separately in that mesh box to enable them to be at 25 c and increase their metabolism to ensure they grow well and take in maximum food. They appear to be happy. I can fully understand why you are a Medaka hobbyist. It is great fun and satisfying being new to it myself. They are hardy fish that tick every box for me. Only goldfish / koi are hardier as they'll lay eggs in cooler waters. I have an outdoor pond containing goldfish, orfe and koi. When some of my Medaka reach adulthood and 4 cm will I be able to place them into my outdoor pond with the larger fish. I don't think the larger fish will eat the Medaka but could be wrong. You have been so generous with your knowledge but I'll stop asking questions going forward I promise. Thank you for your generosity!

Respectfully, I have a different understanding of the pH of rainwater. My knowledge is limited, but it appears that in pristine areas of the world, theoretically, rainwater has a pH of 5.6 due to precipitation dissolving CO2 to form weak carbonic acid. In areas such as Tibet there is alkaline dust in the air and rain pH may be above 7.0. In tropical rain forest areas there are organic aids in the air and rain pH may be about 4.5. I don't know anything about the UK but this 2022 map nadp.slh.wisc.edu/filelib/maps/NTN/pdfs/2022/pH_2022.pdf shows rain across the USA is within a pH range of 5.0 up to about 6.5. In my area rain pH is about 5.0.

The "hoops" are filter media ceramic rings threaded onto a long zip tie so they are easy to pick up and move around. I take the ceramic rings from my pond's trickle filter so they already contain beneficial bacteria to help deal with ammonia etc when I put them in the fry containers. The rings also introduce micro-organisms into the containers for the fry to feed on. I initially quarantine the rings for a week or so to ensure they don't have bad stuff on them.

Thanks for the suggestion. That's an option, but I've been happy enough with my overall medaka keeping results so I haven't previously introduced that added complication. However I'm now trying something similar and possibly that'll be the subject of my next video

@@km-qh3rs sounds good. im new to medaka raising my first lot indoors. wish I had a garden to have pots like yours.

I have had breeding groups produce a few eggs when the medaka were about 15 mm long ..... so 2 cm fish should be mature enough. I've had a group of 9 fish producing zero eggs ..... but then I found they were all females. I've also found, depending on the medaka strain, some will produce eggs with water temp at 20degC ..... others won't produce eggs until water temp exceeds 25degC ..... most will not produce eggs when water temp exceeds 30degC Some are OK with 11 hours of bright light ..... some need 13 or 14 hours of bright light. Some produce eggs in relatively poor water quality ..... others need good water quality and/or neutral to mildly alkaline PH. Some medaka seem to spawn better when moved to a tub in the sun ..... particularly early morning sun Some females properly attach the eggs to spawning mops ..... others scatter the eggs anywhere. And some groups (and I have one now) don't produce any eggs, even though the fish are fit and healthy and I've tried every remedy I can think of. One option to try ..... in a group some medaka may steal and eat the eggs from females and/or there are so many fish swimming around it disturbs the spawning process. Perhaps try dividing out into breeding trios of 1 male and 2 females and keep in separate bare containers i.e. no substrate and only very minimal floating plants. Say, 20 liter buckets ..... high protein food ..... with a bit of early morning sun...... maybe 15% water changes every few days.

@@km-qh3rs ah thank you very much for the very detailed response. I really appreciate you taking the time to give me those tips. I will try them and it is interesting to hear that you've had Medaka of 15mm length produce eggs. Perhaps they are breeding but my tub is heavily planted which may be a reason why I am not seeing anything. I will try your suggested steps and see if it brings me any success. Thank you very much once again! :)

@@H.Ali_08 One thing I forgot about and left off the list is ...... perhaps don't expect to get very many eggs if the medaka are in a heavily planted tub. Probably many would disagree with my opinion, but I've got no idea why it is often recommended that medaka need heavily planted tanks or tubs. Medakas' natural habitat is mainly open water streams and rice fields. They are surface feeders with upward pointing mouths and their eyes are towards the top of their head so they can more easily see overhead predators ..... and they need at least 12 hours of bright light to spawn (ideally with at least part of that period being sunshine). They will still survive in a heavily planted environment but will be under stress and many appear shy because ..... they can't feed properly from the surface ..... they can't see sideways properly to look for predators perhaps hiding in the the plants ..... they don't get enough bright light within the murky depths. Medaka are at their happiest and healthiest and most likely to spawn in a sparsely planted tub with a relatively large open water surface area and with bright, good quality, full spectrum light. Sorry, long-winded as usual ....... but, as with my videos, I don't have the patience to edit

@@km-qh3rs this is fantastic information thank you. In fact as per your previous advice I removed a number of plants from my tank yesterday. It's great that you are doing these highly educational videos. I think more and more people in the UK are becoming aware of how great Medaka are!

@@km-qh3rs I have purchased an aquatic thermometer and note the water temperature is around 16 degrees Celsius. I note in your earlier comment that Medaka will not produce eggs generally under 25 degrees C however in exceptional circumstances some may produce eggs at 20 degrees onwards. I just have to hope June in the UK brings warmer weathers which will raise the water temperature to around 25 degrees. Atleast this reassures me why my Medaka have not produced a single egg despite being between 1.5cm - 2.5 cm in length. Thanks for your help. I purchased Medaka fish as they are brilliant, versatile fish that tick every box as I'm sure you will agree being a huge hobbiest of the fish.

Thanks. Problems of similar severity to the PH crash are occasionally to be expected when adverse weather conditions occur and you're trying to keep medaka or other fish outdoors. I've had tree branches blown down in strong winds; toxic leaves falling in the tubs; blocked outlets in the tubs causing fish to be washed out of the tub during heavy rain. I've had a bird dying in the pond and polluting the water; etc; etc. I've seen where people have had their tubs destroyed by racoons and similar animals. As a general issue, water temperatures in my tubs may reach about 35degC next month at least half the time. The resulting low dissolved oxygen content at those sorts of temperatures will start to put stress on the fish. At temperatures higher than that, the dissolved oxygen content decreases further e.g at 40degC, there may be considerable stress on the fish. If I have, say, 15 medaka in a tub then I'd expect to lose at least 3 or 4 or even 5 of the weaker fish by the end of the summer due to high temperatures and/or high rainfall and/or high winds. I've probably got more than enough eggs already. No more goldfish ..... the bioload produced by those 5 goldfish was probably equivalent to the bioload produced by 100 medaka ..... at present, I'd rather have another 100 medaka in the pond rather than add new goldfish.

Hi, it's interesting that, once fry reach about 3 or 4 weeks old, I don't see any newly hatched mosquito larvae in their container. Obviously the fry can't eat older mosquito larvae but perhaps the fry are then big enough to either eat the mosquito eggs or newly hatched larvae. Medaka are quite voracious predators and I'm now beginning to wonder if adult medaka are able to eat dragonfly eggs or newly hatched dragonfly larvae i.e. if you start out with a tub with zero dragonfly larvae and you have adult medaka maybe there's no need to worry about dragonflies laying eggs in the tub. I haven't seen any references to this and I don't necessarily believe what I've just suggested ..... so I still cover tubs and pond with netting to keep dragonflies away.

@@km-qh3rs You make a very good point. Timing is so important. This is my first tubbing season so still lots to learn.

Hi, thanks for the comment. Sorry, I've not heard anything about that. However I think there are very long lists of similar prohibitions of plant and animal based items in many countries. However these lists are often so obscure and hardly promulgated that most people are unaware of what may or may not be prohibited.

@@km-qh3rs thanks for the detailed response. I think you are spot on. Thanks and keep up the great work! Look forward to seeing more of your videos re Medaka

Yeah, I also watch a lot of youtube videos at x1.5 speed. My wife often tells me she wishes she could listen at x1.5 speed when I'm talking to her.

If you are getting lots of eggs from your medaka then no need to worry too much. Most of them will hatch without too much care. But with only 15 eggs I assume you want to try to get maximum success rate. Depends on what sort of system you will use but some suggested points to think about. 1. White mold on eggs kills the embryo. So keep a space between all the eggs. 2. Optimum temperature for hatching eggs is about 28degC. Hatch in about 1 week so less time for mold to develop. 3. Hatching at 20degC takes about 2 weeks so more chance for mold to develop over that longer period. 4. Eggs in a small container at 20degC maybe water change 20% to 100% every 1 or 2 days. Eggs in a large container at 28degC maybe 50% every 3 days or maybe no change. 5. Fry are very very delicate for first 2 weeks. Risk of being damaged by change in water conditions or temperature. So only minimal water changes during that period. 6. If fry hatch in small container then only transfer to larger container that has very similar water conditions as hatching container. Transfer by scoop and NOT by net. 7. For first 4 weeks I change water by drip acclimating method. I change 20% each time. 1st change at end of 1st week. 2nd change at end of 2nd week. After that, change every 2 to 3 days during weeks 3 and 4. And maybe continue at that rate for another 4 weeks if I'm really keen on getting good, strong, healthy juveniles for that type of medaka. 8. Some fry feed only 2 days after hatching. I've found some feed immediately. So I feed immediately after hatching. 9. I've heard of the brush feeding method. I feed using a small, long-handled spoon as shown in my video Fry Management - Food. I think it's easier to gauge quantity that way. 10. The above are only suggested points to think about for eggs that are important to you. You could probably ignore most of them and still get a good success rate. Good luck.

Hi. thanks for commenting. I'm honestly OK with receiving any feedback. However I have no ambitions to be seen as an "influencer" or renowned expert on medaka. If you listen to the intro to my first video on Jan 6 you will note that I'm a really old guy who decided to find out how difficult it is to start a youtube channel. Talking about my medaka was the first thing that came to mind and I didn't expect to produce more than 1 or 2 videos before deleting my experimental channel. Yet here I am 23 videos later .......... I fully appreciate your point of view but regret that you'll have to look somewhere else if you want slick, concise, high impact videos. I sit down with my battered, old, no brand name Chinese smartphone and ramble on talking for about 15 minutes ..... another 10 minutes minor editing and uploading to my channel. For me to make a slick, high impact video would probably take me 2 to 3 hours scripting it, re-shooting various clips, dealing with sound issues, major editing, etc, etc and I don't have any interest in that sort of stuff. My type of channel is an amateurish, personal video log, vlog, about my medaka on an approx weekly basis and I think I said in my first video that probably 99.9% of people would find it boring. So I now continue it as my own personal vlog and I'm happy if there's anyone else who finds it interesting enough to watch. I fully accept that it will appeal to a very limited audience. The analytics show that an average of about 300 people start to view each video. About 50% or 150 viewers very quickly switch off within the first 30 seconds. There is then a slow decline in the number of viewers as the video progresses but there are still about 25% or 75 viewers who watch the whole video. I'm happy with that.

Thanks. I usually feed all the fish twice a day. But the important issue is how much food to give. It appears the advice sometimes given for aquarium fish is to give the amount that can be consumed in, perhaps, 2 minutes. I haven't actually timed it, but my guess is that I give the outdoor medaka the amount that they can eat in, at the most, 20 seconds. But also the amount I give depends on water temperatures. If it rains all day, maybe I don't feed them at all. I think that in very many areas outside of Japan, including my area, it's really hard, if not impossible, to find medaka for sale from commercial sources. Perhaps similar to my area; very, very occasionally it may be possible to find a private source on local social media but even then , prices for the cheaper (say, red/white) medaka are probably about US$7 and it's necessary to travel to pick up at the source. Very limited range of types available but prices of those with lame, long fins, etc may easily be double or treble the cheaper type. Also more expensive for a matched male/female pair.

I assumed you would have many options to buy medaka locally. We are made to believe here, that medaka are very common in your neck of the woods.

@@andreagalda28 Again I emphasize I'm not an expert ..... but I think that medaka are only easily available in Japan ..... and there they can be obtained from home improvement stores to specialist medaka shops to roadside stalls to online stores to local weekend medaka street markets etc etc etc. As far as I'm aware, almost everywhere else outside of Japan, including the rest of Asia, they are hardly known, usually difficult to obtain, usually limited varieties and usually expensive. I haven't been to a local fish shop for a long time but I expect they still don't have any available. I don't live in Singapore and I've never been to this Singapore shop, but as an example of prices you could look at madshrimp.com which lists online red/white medaka for sale at US$6 each.

Thanks. I live in Asia so couldn't send any fish to you in the UK. However I wouldn't sell fish anyway. My medaka are quite plain and standard and, although maybe similar to pure bred strains, are probably hybrids of different strains. So I couldn't call any of them pure bred and buyers would probably be disappointed with what they received.

Thanks, maybe you only crossed your fingers on one hand ..... had eggs for 3 days from the yozakura ..... but none from the red/blacks. So only leaving one male in a breeding group is an option worth trying. I mustn't complain too much ..... but only 1 female yozakura is producing eggs and unfortunately this female is probably the least well-colored of the group of yozakura females. Just for information ..... it must be the first time this female has produced eggs. Day 1 was 2 eggs; day 2 was 3 eggs and then 12 eggs on day 3 ..... however the female has not yet got the idea of depositing eggs one at a time spread out on the spawning mop. The 12 eggs were deposited in one place like a bunch of grapes. Interesting how eventually females instinctively start to deposit eggs individually.

Thank you for the information. I'd vaguely heard about this sort of situation but had never come across an actual example. I have been syphoning out the debris at the bottom of the tubs and sieving it to try to find if the females have been scattering their eggs but have not found any. Last year the red/black females attached their eggs to the sponge filter but I have not seen any this year. In fact I have been checking the fish every morning but have not seen any females carrying eggs therefore I assume the medaka have not gone through the spawning process. I'm hoping that changing things to 1 male and a few females will stimulate the process. A good idea though to place a spawning mop on the bottom of the tubs to see if that helps. I may also add a mop made of knitting yarn to see if the females prefer that. Thanks again.

Wow, I'm sure you get excellent results with that system and I can see how it might be interesting to set up and run.. However, my experiences with the natural eco route of green water, micro-organisms, etc has resulted in very variable results. Personally I think I don't have enough patience to set up and properly maintain a natural system like that. For my more valued medaka I'm happier with my simple, controlled, clean water/powdered fry food system that, for me, produces consistent results. For my basic medaka that produce lots of eggs, I'll often just throw a spawning mop with eggs into a bucket of pond water with floating plants and see what I get a few weeks later.

Thanks

Almost anywhere outside of Japan, I suggest it's probably really hard to find medaka for sale. Very occasionally it's possible to find a private source on local social media but even then , prices for the cheaper (say, red/white) medaka are probably about US$7 and they have to be picked up at the source. Very limited range of types available but prices of those with lame, etc may easily be double or treble the cheaper type. Also more expensive for a male/female pair.

I think sometimes you might read that medaka jump out of aquariums, but I don't keep my medaka in aquariums so I couldn't comment on that. However I have never had any medaka jumping out of my tubs or pots. I suggest that if you maintain good water quality conditions and a tub or pot is not over-crowded, then it is unlikely that medaka would try to jump out.

Thanks. I'll emphasize I'm not an expert ..... this is just the way I do stuff.

The 6 grow-out tubs are 35 liters each ..... about 9 gallons each. I think if you see my grow-out tubs video, I did a simple calculation something like ..... with a small sponge filter in a tub, stocking ratio can be 1 medaka for 1 liter of water - so each 35 liter tub can hold 35 medaka - 6 tubs gives me my required production of about 200 medaka this breeding season.

Yes, exactly that, I sort through the plants to find the short-root sections ..... however once I've got some I find at warm temperatures they can reproduce similar size plants very rapidly. Also the goldfish in my pond love to eat the roots of the larger plants but they never manage to keep up with the reproduction rate of the small plants so I have a large reservoir of small plants available if I need more. My spawning mops may get a small amount of algae on them sometimes but I've never found them to get yucky so I never clean them. When I finish collecting eggs I rise the mops in tap water and leave them in the sun for a few days to dry.

I don't bother spending the time breeding any live food such as mosquito larvae, daphnia, brine shrimp etc. I figure that medaka outdoors get enough of a varied diet from small insects etc that land on the tubs' water surface. Incidentally, I find that once medaka fry get to about 3 weeks old it seems they are big enough to eat mosquito eggs on the water surface. With fry less than 3 weeks old the mosquito larvae hatch out ..... fry older than 3 weeks then no signs of larvae. I've kept fish outdoors for many years. I very quickly experienced the problems of herons and dragonfly larvae eating the fish. Since then I've found that both the heron and dragonfly the problems are solved if ponds and tubs are covered with 10mm mesh netting. See my videos on my pond and the DIY video showing my netting covers for my tubs. I've often observed dragonflies hover about 1m above the pond; apparently see the netting, which I keep at least 50mm above the water surface, and immediately fly away somewhere else. It's a long time since I had a dragonfly problem.

Asia ..... with a sub-tropical climate.

@@km-qh3rs makes sense, I was hoping you were in the U.K. so I could buy some eggs 😁

As you say, there are always more ways of doing things and it depends on objectives. So, I'm not arguing against your system but, personally, my objective is to raise reasonably valuable medaka fry by using a method to try to maximize the success rate for eventually producing strong, healthy, juveniles with good coloration. With that objective, there's no way I'd use strong green water. Plain green water consists of phytoplankton which are plant-like organisms which are not suitable as food for carnivore medaka fry which need a high protein diet. Zooplankton can be added to plain green water as a source of protein for medaka to feed on but this means adding pond water or old aquarium water which increases the risk of disease or damage to the health of delicate medaka fry. Medaka fry are delicate for the first 2 weeks. After about 4 weeks I transfer the fry from the "sterile" containers to 35 liter outdoor grow-out tubs which probably contain just about every type of micro-organism you can think of ...... but there's still no way I'd deliberately use strong green water ..... too much (for me unnecessary) risk of, for example, low dissolved oxygen levels; adverse changes in PH levels; high bacterial levels, etc which cannot be seen in green murky water. Also, I don't want to have a fast growth rate for the fry. My objective is to produce juveniles which have the best coloration I can get from the particular medaka strain's genetics. It's my understanding that a fry's body structure may grow fast but, (and this is a massive simplification), the production of the pigment color cells in the skin of the fish may not be able to keep up with that fast growth rate. Generalizing, a slow/moderate growing medaka fry/juvenile will probably finish up with better coloration than a fast growing medaka fry/juvenile ..... perhaps this particularly applies to medaka strains with a lot of lame/shine etc. But I'll again emphasize I'm not an expert ..............

The black medaka, orochi, would probably be a good choice. I think they are reasonably tough and not too difficult to breed for a beginner.

Wow, thanks for the compliment.

Because plants are not necessary and placing them in fry hatching containers increases the risk of introducing mold, disease, etc into the containers. For the first 2 weeks, fry are very fragile .... raising them solely in clean water without plants and other stuff increases the survival rate of the fry.

Yeah, I'm thinking that my next video will be on that issue.