Goldfish once floating...now on the bottom

Question
Hi Chris

I have 3 goldfish in a hexagonal tank that holds about 20L or so.  I am feeding them goldfish flakes from the aquarium centre.  The tank has a good filter system and I change a % of the water pretty regularly.  

Soon after getting the fish 1 of them appeared to have been suffering from intestinal gas and following a look at your previous responses I fed the fish cooked peas and it did the trick.  

I have recently gone on holidays for 2 weeks and put a Wardley Premium Vacation Food block in the tank which was meant to last 14 days.  My friend who was checking in on the place every few days said the block of food apeared to have dissolved in the first 3-4 days.

Since I got back the once floating goldfish is now firmly sitting on the bottom galping its little heart out.  Fearing oxygen deficiency I changed around 50% of the water to clean it up a bit.  Since there was no evidence of the food I put a little bit of flakes in which the healthy fish ate a couple and then seemed disinterested.  They are swimming well, responding to movement around the tank and eating more now.  I tried peas in case that helped but the sick goldfish has been on the bottom of the tank for a couple of days now and doesn't eat or swim or move or anything.  

What can I do to help him?

Answer
Hi Trina;

Poor guy has lost the use of his swim bladder. Make a 25% water change every day until he feels better. It may have been brought on by the food block. Goldfish just eat way too much too fast and it causes pollution and often other health problems. There isn't really anything else you can do but hope it heals and starts working again. The swim bladder is an organ that controls buoyancy. When the fish wants to go up in the water it inflates with blood gasses. If the fish wants to sink down the blood gasses dissipate. When this organ fails, it can't hold the blood gasses and the fish stays on the bottom. Many hobbyists try a fish antibiotic called "Maracyn 2" to combat possible infection, but once the SB fails it still may not heal enough to work again. Maracyn 2 absorbs inside the body unlike other medicines that only treat the outside of the fish.

The good news is that many fish live a very good long life in spite of this condition. They don't appear to be in any pain they just get frustrated at first trying to swim. They get used to it and adjust eventually. If you find that he can't get enough food while in with the other fish or his belly gets irritated from sitting on the gravel too much you might want to get him his own tank. Don't put any gravel on the bottom and get one that is at least 10 gallons. Put a good filter on it and use sinking goldfish pellets as food so he doesn't have to struggle to the top to get them.

Be sure you make 25% water changes every week for all your goldfish. They are messy fellas so nitrates will build up causing them to be prone to this and other kinds of problems.

Hope he feels better soon.....

At Your Service;
Chris Robbins