Goldfish are quite possibly one of the most abused pets in the UK. They can be fantastic first pets, but the out-dated myths of their care means they're often left in terrible conditions to suffer and die long before their time.
Goldfish FAQ
1. Goldfish are classed in two catagories. Common and Fancy. Common are best kept in ponds, whereas fancies are selective-bred therefore more delicate, often having difficulty swimming, so would not survive in a pond and must be kept in a tank. Click this link:
[link] It has a fantastic list with pictures of each type of goldfish currently available. The Common, Comet and Shubunkin would survive in a pond, the others are best kept in a tank.
2. They are coldwater fish and must never be kept at tropical temperatures. If kept at tropical temperatures their metabolism will increase leading to all sorts of health problems, and any tropical fish kept in with them will suffer from the increased ammonia created by the goldfishes waste.
3. So you want to keep a couple of goldfish in a little tank. Forget it. Goldfish need BIG tanks to thrive. Follow the rule of 20 US gallons for the first goldfish and 10 US gallons per fish thereafter and you'll be on the right track. So your 3 little goldfish will need at LEAST 40 US gallons of tank. And a long tank at that! They're lateral swimmers. Keeping them in tanks too small will mean they'll again suffer from ammonia poisoning, cramped conditions, you may think they're happy, but really they're not! They'll all suffer from growth problems.
4. Goldfish also poo, a LOT, therefore you must never skimp on filtration or tank cleaning. The tank MUST be cleaned at least once a week with a thorough gravel vacuum to hoover up all that poo. Aeration is also important, goldfish like a lot of oxygen in their water, so bubblers are recommended. Plants also add oxygen, but your goldfish WILL eat them.
5. Common Goldfish have the potential to reach 12"-14" long. Fancy Goldfish will reach 10"-12" long. Kept in the correct tank conditions anyhow. Goldfish are long living fish, the oldest on record is 42 years old. Their cousins the Koi Carp have japanese legends of them living over 200 years and passed down through human family generations. So when your goldfish dies after 2 weeks and is only 2" long, no this is not right.
6. Do not be tempted to buy sick looking fish in pet shops because you feel sorry for them. By the time they look sickly it may be too late to save them, and you'll be putting money in a fish stores pockets that doesn't care for it's fish properly, they'll just fill the space with another sickly fish. And never EVER endorse the fairground tradition of giving out goldfish as prizes.
7. There are very few fish that make good goldfish tankmates. Do not keep plecs with them (sucker mouth catfish), they're tropical fish and will suffer from ammonia problems spending a lot of time on the bottom of the tank with all your goldies poo. Also be aware goldfish have a habit of eating anything that will fit in their mouths, and the potential of choking on anything that doesn't (so barebottomed, sand or very large pebbles make for the best tank substrate, rather than gravel). There have been successes however with zebra danios, white cloud mountain minnows and large apple snails. Snails also poop a lot however, and a slacking danio or minnow could be inhaled by a large goldfish. Goldfish are best in species only tanks.
8. Feed goldfish a mixed diet. The fancier goldfish with short bodies are prone to swimbladder problems, so feeding them greens like cooked peas will help them digest their food and avoid constipation. Also let the food sink before the goldfish eat them, letting them gulp air can also lead to swimbladder problems.