Possibly a swim bladder problem, swim bladder problems are due to swelling of internal organs. This puts pressure on the swim bladder. Could possibly be an infection or parasites. Or it could be trapped air, from feeding fish flakes, as when the fish takes the flake in he takes a large gulp of air too.I just noticed today that my tiger barb in my 40 gallon low tech planted aquarium is swimming oddly anybody know what this is?
It's probably from ingesting too much air when feeding.
If you feed dry floating foods like flake, stop feeding that for a couple of days and use frozen (but defrosted) or live food for a bit and see if it fixes the problem.
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Your black angelfish looks like it has slightly clamped fins. Do a 75% water change and gravel clean the substrate every day for a week. Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
Clean the filter if it hasn't been done in the last 2 weeks. Wash filter materials in a bucket of tank water.
If you are going on holiday for a week or two, just feed them more often before you go and they can live on fat reserves while you're away. Do daily water changes and gravel cleans when feeding more to keep the tank clean.
If you are going away for more than 2 weeks, measure out some food into small containers and get someone to feed one container to the fish, twice a week. Each container should have one portion of food that you would normally use.