i have two baby black arowanas about 5inches in 250g tank with some clown loaches and frontosas. two days ago i noticed one of the arowana is swimming halfway down the tank and they usually only stay on top. yesterday, it was swimming on the bottom of the tank. i tried feeding it but did not eat anything for the last two days. the other one is eating and swimming on top. checked the water parameter and everything is fine. so i got the sick one in another tank. raised the temp to 86-87, added aquarium salt and metafix(?). today, it is swimming on top again and eating one or two pettets. how long should i keep it in the hospital tank for?