high mortality goldfish

Question
I work for a large retailer in the US. I run the pet dept. I have been having trouble with my common goldfish when I receive them. Usually they are bagged the night before I get them due to the distance of thier trip. When I release them they do ok for about 3 hours or so then most of them lay on the bottom of the tank. I have tried to give them peas. I add stress coat and salt to my tanks . They get stress coat when they are delivered too. My system is a 110 gallon marine land unit. It has carbon filters, prefilter, a bio wheel and uv. I am having so much trouble.... Is there anything you can tell me to help me out. I am not allowed to add alot of things to the tanks without uppermanagement permission. Also how do I know if the bio wheel is ok of has died?

Answer
Hi Nettie,

Any treatment you put in there is going to be pushed into other tanks by the filter which will end up causing stress to other fish. So I'm guessing we've got to stay clear of chemical treatments.

This 110G must be a very well established Aquarium so even if the bio-wheel has died there must be a sufficient build up of bacteria in the holding tanks to sustain the fish. The only sure-fire way to check your bacteria colony for life is to check whether water is flowing through the filter. Pennplax make emergency pumps that will kick-in should your filter break down. However sustaining a 110G might require a fair few pumps! == If the bio-wheel has gone down, aerate the tank manually, keep bacteria colony damp and set about replacing it.

Alternatively, it could be a Water Chemistry problem. Your bacteria will consume nitrite and turn it into less harmful nitrate. Aquatic plants take in excess nitrate thus keeping the cycle flowing freely. However holding tanks are often overstocked and sparsely decorated. High amounts of nitrate can be toxic and a water change is the only way to fix the problem.

Thirdly it could be an actual batch problem. Goldfish are commonly effected by swimbladder. They are prone to constipation, deflation of S/B organ etc. Flake will swell in the gut and cause SBD symptoms but often the fish will recover after a couple of days at most. Swimbladder disorder itself is not fixable, raise water temp. by 2 degrees slowly, drop water level to 4" and feed earthworms and Daphnia. Alternatively a 3% salt dip can offer some relief.

Sorry I couldn't be much Help!

Good Luck!

Please reply to me ASAP!!!! I have some info. that I've omitted from this answer because I need to confirm it!!

Tom