why are my older fish dying w/ new ones in tank?

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Hi Laura;

How big were the goldfish? One was 3", the other 2" head to fin end. (One was a mini black moore gold fish and didn't grow much, though the other I had from a little baby and he grew to 3")

How big were the other fish when they were with the goldfish? none are larger than an inch- mabey inch and a half, and the catfish was about 3"

How often do you make water changes? How much at a time? usually 1 gallon each week/every other week

How often do you clean the filter? It's an Aquatech filter for 10-15 gallon tanks and I change it every month per directions

What kinds of foods do you feed? How often? TetraFin Goldfish flakes every day, just a sprinkling. I also give them Tetra Baby shrimp sun-dried treat twice a week apart from regular food.

Thank you so much for helping me! I'm afraid I did something wrong, and really would like to avoid it if I am.
*Laura*

Answer
Hi Laura;

I think overcrowding and not enough water changes is the problem. Goldfish are very messy and deep-bodied fish that need plenty of room to make their mess in. Since they didn't get very big after having them alone 2 years is an indication of not enough water changes. The answer is to make 25% water changes weekly, no matter what kind of fish you have. All goldfish get to be 6 to 8 inches long as adults. There is no such thing as "mini" goldfish. He just never got up to his potential I'm afraid. Once they get about 4 inches long you have to move them to a 20 gallon or larger. Especially if they stop growing.

Your ten gallon tank can only handle a total of 10 inches of fish. You have to consider the adult size when you calculate the population. The little "tuffies" (Aka "shiners" or "minnows" as they are called here) would be fine to have, but no more than 3 or 4 and nothing else can go in the tank. They get 2 to 4 inches long. Whatever you decide to keep in there, now you know what to do to help them thrive.

Followups Welcome

At Your Service;
Chris Robbins

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