i had them in a 1 gallon tank with no filter. i use AquaSafe Water Conditioner for the water.i feed them wardley essentials-goldfish flakes and i give them 1 pinch per goldfish. my other goldfish bubbles eats his food in about 30 seconds and then heads to the rocks in the bottom of the tank to find more to eat.i couldnt find any sign of illness.bubbles is acting like nothing happened, just being normal like there never was another goldfish with him.