Good Luck Bro, Nice to see you back but not under these circumstances. I miss those Tropheus. Keep us updated on that tank.

The surface of your water looks really calm. Another hobbyist shared not long ago he had two canisters on the tank but they were creating no surface agitation and he oxygen-starved some fish just a thought

Oops didn't realize how old it was..lol

Any update?

Did you check your city water if they might have changed anything? If you did what you would normally do then that would be my first thing to check

Is the plants new maybe contaminates on plants like fertilizer slowly poisoning the clouds

when my glass fish started gasping for air it was the ph lvl being to low for them they were shareing tank with my shrimp moved the glass fish out to a "normal" ph lvl tank and they improved imeadately so id suggest check the ph

It's most likely your tap water. Switch to bottled water.

The title should be changed to " I have a damn airstone and the pump is on 11 " 🇨🇦 🌪

Likely internal parasites or worms, happened to me, usually die of fairly quick organ failure, try and find a medicine that treats internal parasites. Especially if they fish are fairly new to the aquarium, I have found that they may do fine for a month or so before they drop pretty quickly, white clouds and other cheaper fish sold in large quantities are often ver susceptible to parasites because they are kept in often less than satisfactory conditions at a wholesaler. just my observation and experience maybe totally wrong. Good luck

At the 2 minute mark is that white stringy poop?? Looks like they have some kind of internal issue

White clouds are extremely hardy. They may have a disease from purchase time. You could try quarantining them and testing the water for ammonia fluctuations. Make sure no one is spraying anything in the room like febreeze or anything else we tend to use in kids rooms... ny wife was speaking lysol and killed some very expensive fish till I caught her in the act.

A few questions.. How old is the set up? Whats the Water ph? Have you got a Co2 system for the plants? do you have a carbon filters and if so how often fo you change them?

Were all the fish added at the same time? If not were they quarantined? Last water change? What conditioners do you add to the water? What's in your filters? Also I see you dont have much surface movement. Your returns are under the surface and not moving it at all.

You need to have surface agitation, so that the gases can evaporate this is why your fish are gasping. Get a nano circulation pump and aim the flow towards the surface so you have a ripple effect. I have an aquarium and you really need the surface agitation. Hope this helps 👍

Have you checked the following pH kH GH Calcium Iron Copper Phosphate Potassium Silicate Iodine and Iodide

My first suspect would be the wood in the tank remove it and do a 💯 % water change over a 2day period

It almost seems like the water is contaminated. Did you have something on your hands and stick them in there. Do a 25-50% water change. Try increasing the surface agitation. Point your out takes towards the surface.

Might need some more water movement

Check the temperature of the water. It doesnt matter if your house is 70-80 degrees. it doesnt mean your tank will be the same. A reliable stable water temperature is very important. I use to have a cheap heater in my aquarium and my cardinal tetras kept getting ich and cat fish dying. I checked everything under the sun and it turned out to be a unreliable heater.

What are you water peramiters? pH ammonia nitrites and nitrates. Start with the basics.