Black arowanas are not hard to raise but If you are getting small ones then expect some problems. Get ones about 12" and raise them together and you will have no problems. Don't expect to raise multiple black arowanas in a 55 gallon for any period of time as it's too small and will just stress them out. Bigger tank, bigger aros, better luck!!
I missed this post. I have to disagree with most of the post. I have raised my black aros this round from 2.5" without many issues, aside from some minor aggression. They started in a 15gal with 10 others. That was for a few days. Then my three went into a 40 breeder. The others were sold. I kept my three in the 40breeder for I think a month or so. Then once they reached a comfertable size 5" or so I moved them into the 125gal. That move started some fin nipping and singling one out but it seems to have passed.
Bigger is better, but sometimes they need to have some limitations to reduce aggressive behavior. Do take that the wrong way and say that I think they are always less aggressive in cramped conditions or that they should ever be in them. My aros were not cramped but content and adequately housed with steps up as needed.
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