I do keep them, used to breed them but just kept my remaining stock in a comm with the ray.
I think that a varied diet is the best you can do. I heard people freeze a variety of sea food for stock upto a month.
Have to agree with you there, rays are easier to keep than lets say discus or dats.
About your point on fresh air lets just go midway here. If you have the luxury and the time to do a daily water change then thats all well and good. But for us who can't, we rely on beefing up our filters to keep our water clean as well as the weekly water change. Been doing it for 10 years and it hasn't failed me yet.
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