Why does my goldfish swim upside down after feeding?

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Dave Hulse offers advice to a PFK reader whose goldfish is experiencing buoyancy problems.

Q. I have two Ryukins in a 200 l/44 gal tank. One of them has started to have trouble swimming and I think it must be something to do with his swimbladder.

Sometimes it’s OK and swims around normally, but it seems worse in the evenings, after feeding, when he seems to have trouble staying the right way up.

I give the fish flake and pellet food for goldfish. The water conditions are all testing OK and at the moment the other fish seems to be fine.

J. Davies, email

A. Ryukins, like some other fancy goldfish varieties, are especially susceptible to these kinds of problems, as their fancy body form contorts the spine and internal organs, placing greater pressure on the swimbladder.

Also as the fish takes extruded pellet or flake food from the water surface, it gasps in air which can enter the swimbladder, again causing buoyancy problems.

It does sound as though this problem is due to excessive air intake during feeding, especially as your fish seem to be otherwise OK.

Feed a quality sinking pellets food to minimise air intake and offer bloodworm and similar 'wet' foods on a regular basis. Bloodworms help by encouraging the passage of food through the intestine, which can dislodge any blockages that might lead to swimbladder problems.

Fasting your fish for a couple of days may also help.

Dave Hulse

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