Hi, I have a spawn of betta fish that all the fry swing whith it’s tails down. I read that is something call dolphin swin….but why it is happening? I spawn my bettas in a plastic recipient with 3” of column whater and dimensions of 8”x16”. The fist weeks everything is ok, but about 5 weeks old, all of them swin in bad position. I feed them whith artemia nauplids. Thanks for your advice!