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 ..............

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!