Aiming4 Goldfish Care

Just a random thought while I was running at the gym. I don’t keep my goldfish in bowls. They are in a 50 gallon with a Fluval 405 canister filter and a 30 gallon with a AquaClear filter. But I have wondered this for a little while, why does everyone say it is cruel to [...]

I plan to get 2 ranchu/lionhead goldfish
I have a 29 gallon tank; it is used, but I just got it
1) I forgot..what do I clean it with again before I fill it?
2) How much do I fill it up to? I know it has to do with oxygen or surface area or something. Do i [...]