We have had a largeish tank for the last year with goldfish in, the first lot all died leaving us with 2 small catfish, we haven't had much luck since then we had 2 goldfish seemingly doing well, for 3 months but one just died!  I hsave just bought a loach 2 weeks ago and a goldfish, the loach is doing fine but the goldfish is sitting on the bottom! not happy at all, we have tried everything, water changes, water testing etc but I just dont understand what is happening as it only effects the goldfish, they are just your bog standard fish! not the fancy ones any help would be really appreciated cheers Cathy

cath987; The next time you bought the new gold fishes back, place the entire bag of goldfish onto the tank for at least half hour to nominise the water temperature in the bag to that of the tank temperature. Once the temperature is almost the same, you can either drain away some water or pour the entire pack (water plus fishes) intothe pond or tank. Goldfish are very sensitive fishes. you may want to put a heater into the tank to maintain the water within the tank to around 23 deg C.They are like human, they do not like temperature swings. Oh, when you choose the new batch of gold fish, choose those that are very difficult to net. Son't ever net those that are easily net up. Hope this helps.