I moved my quarantine fish into my 20k pond, but found all of the fish are now picking on the fantails. One fish in particular was being pushed around like a soccer ball, they literally pushed it with their noses till it bounced around, every which way, including upside-down.
I moved the fantails back into the indoor quarantine tank, but I'd really like a more permanent habitat for them, as I don't feel its very humane to keep fish in a small tank and also like to see them swimming more. Within the pond, the fish zip around, but in a tank, they just bob about and bump into the glass, which I assume isn't a happy life.
I already intended to buy several small half-barrel ponds around the house, with their own little fountains, filtration, and plants. Each is 37 gallons.
Would these fantails likely be happier if given their own 37-gallon planter? Or better to place them in pairs, sharing the 37 gallons between 2 or 3 fantails, though they'll be more cramped?
Now they are only 2" fish, but I know they can grow quite large.