stunted growth area

Question
Hi, Chris. I have a chebunkin goldfish and along with another they have both been happily living in a huge bowl above my fridge. After only one year I noticed this one was growing normally from the head up to the dorsal fin then everything beyond that was still the same size as when I bought it - half the size of the head portion! It also suffers from  air bladder problem (or constipation) as after three months I noticed it had to dart forward in order to stay vertical otherwise it would naturally swim with its tail over its head. Temperature is a constant 78 and the filter is changed once every 6 months. I am about to give it the pea diet but am concerned about the fact that it appears to be two fish in one, it is so under-developed from the tail back which is recently making it hard for it to swim anywhere as the head is so big in camparison to its dorsal fin and tail area - why is this?

Answer
Hi Sorrel;

The tank is just too small. Shibunkins are a type of goldfish that grow to a very large size of at least 8 inches and are very messy. They require at least ten gallons just for one fish, preferably 20 gallons or larger, in order to thrive. It may be too late now for yours to ever be normal again but please get him into a regular tank with a power filter. His water temperature is too high as well. Goldfish are cold water species that can't tolerate temperatures above 72f for long periods of time. When you get a tank for him, put it down lower in the room where the air is cooler. Here is a web page about goldfish and their needs;

http://www.firsttankguide.net/goldfish.php

At Your Service;
Chris Robbins