bubbles escaping out of gils in black moore HELP!

Question
hi i have had my black moor for around a year now and in the last few weeks he has had bubbles escaping from his gils, (i cant find anything on the internet about it) he also is partly covered in white slime (which i am treating but keeps returning)
he is kept in a 60 litre tank which has a filter and a built in airstone, in the tank with him is two fantails, a small coldwater pleco, a shrimp that lives in the filter and four minnows (i will be geting a 240lt tank soon as its getting crowded)
i change a third of the water every two weeks and clean the filter once a week, i upgraded to the tank  nearly two months ago.

Also one of my younger fantails is also showing white slime, but on the end of his tail and it looks slightly ripped, is this tail rot? if it is what treatment can i put in and can i combine different treatments at the same time? the fantail was stuck in an ornament a few months ago and we had to gently push him out, ever since his dorsal fin has been drooped but both him and the black moore seem fine in themselves and are eating and swimming fine.

Thankyou so much i hope you can help!

Answer
Hi Beckie;

The good news is your fish don't need medication. They just need a larger tank and more frequent water changes. The bad news is...your tank is very overcrowded. For just one goldfish you need at least 40 liters of tank water. They are very messy guys that create a lot of waste even while still small. If you check the levels of the toxins ammonia and nitrite in the tank water you will probably find one or both elevated. In an established tank they should be "zero". Ammonia and nitrite are from fish waste. Your filter and tank surfaces (decorations, rocks, etc) have beneficial (good) bacteria colonies that are supposed to process those waste toxins. There's just too much waste and not adequate bacteria colonies in such a small tank so it's irritating your fish and causing their skin and gills to burn. It can also cause deterioration of fins and eyes, eventually leading to infection and possibly death.

For now, change 25% of the water every other day until you can get them into a larger tank. All tanks need a 25% change at least once a week anyway. Two weeks is a long time to wait between changes with goldfish. Yours needs more right now to help keep the fish alive until the crisis is over. Feed them very small amounts right now too. The more food that goes into the tank, the higher the toxins rise. Feed them once a day and make sure they eat all the food from all areas of the tank within 3 minutes. Goldfish are natural born gluttons so don't let them fool you into thinking they need to eat more. If they beg for food between meals, it just means they've trained us quite well. ;-)

Here are some very helpful web pages, including mine about new tanks, to help you more;

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

http://www.kokosgoldfish.com/tensteps.html

http://tinyurl.com/n94nmb

http://expert-fish-help.xanga.com/

Good luck and I hope your fish do okay...

At Your Service;
Chris Robbins