New Goldfish for Older One

by Ant
(uk)

Hello

We used to have two goldfish which got on great with each other, but sadly one of them died and the other seemed to just stay on the bottle of the tank. So we got two new baby ones to keep him company now he swims back and forth in the tank all day or stays in one corner splashing about and banging into the corner.

He doesn't harm the two new ones but I am concerned about him.

Any help would be appreciated

regards

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Grant’s Reply

Hi Ant
When there is a large change to a Goldfish tank’s inhabitants as has been the case with yours, mostly nothing untoward happens and the original fish carries on as usual.
Sometimes there are two other scenarios:
1. The original fish is upset with its new tank mates and avoids them or
2. The original fish considers the new tank mates as food.
I had the second scenario happen recently. I had three Black Moor in a tank with no problems whatsoever.
I removed two to a pond for sizing and left the third in the tank to be sold. He stayed by himself for several months, often sitting on the bottom.
Recently I put three Moors of a similar size in with him that were also for sale.
The customer arrived the next morning and I found three Moors with shredded tails.
Often, if Goldfish have a change of diet or a sudden drop in water temperatures this can happen.
I checked the other fish I was keeping; they were fine. I observed the tank for a few minutes and caught the original fish chewing on the tails of the 3 new tank mates at every opportunity.
As for your fish being upset with the new ones, you use the description baby, so I assume they are smaller than the original one. If this is correct it is unlikely he is upset.
Did you quarantine the new ones?
If not it’s possible they have brought in some pathogen that your fish hasn’t been exposed to before and it is irritating him.
If the behaviour is still occurring, I would get a parasitical medication such as ParaGuard or API General cure. These both kill flukes (common on small Goldfish) and protozoan parasites.