victimizati0n said:
This may not be the case if they are small. A 10'' goldfish would have 64 times the mass of a 2 1/2'' and would, all things being equal, produce 64 times as much waist (i.e, fecal matter). Obviously the higher metabolic rate of a rapidly growing young goldfish means that the ammount of waste produced will be more than 1/64 of that of a four times longer adult fish but nonetheless the difference in total amount of produced waste is still very large between a small goldfish and a fully grown one. I am currently keeping two fan tails in a 6 1/2 gallon tank. One is 1 1/2'' and the other is 2 1/2''. I have a sponge filter rated for a 20 G tank. Ammonia is zero, nitrite likewise zero whereas nitrate is 8. I replace 1/4 of the water once a week. Basically, in my view, the quality of the water will let you know when it is time to put them in a bigger tank.
