I currently have a 21 litre tank which houses 6 White Cloud Mountain Minnows (Tanichthys albonubes). They are extremely well cared for, with a heater to maintain the water temperature, a filter which is powerful enough to replicate the conditions they would live in in the wild, an air pump on almost full flow to provide the right amount of oxygen, a plant to keep the nitrate levels in check (the filter looks after the ammonia and nitrite levels) and to provide shelter for them, plenty of light for the plant and them, and plenty of variety in their diet.
Very soon they will be re-housed in a tank between 60 and 120 litres with the conditions they are used to replicated, with the addition of some more plants and some new fish added.
You may wonder what I'm getting at with my post title.
Well, when I bought my tank, I was told a few lies which I will now list:
1. 21 litre tanks are suitible for 2 goldfish.
2. The fish will adapt to the tank.
3. You don't need to vary the diet of any fish.
These lies are told by a number of shops which sell these tanks and ones even smaller to unsuspecting people.
21 litre tanks are nowhere near large enough for 1 goldfish, never mind 2. Do not be fooled by this lie. The comet variety of goldfish, given as prizes on funfairs and the cheapest to buy, needs at least 80 litres of water to live in. That's a 160 litre tank for 2 at minimum. The smaller fancy varieties need at least 40 litres of water.
Yes, it may look like the fish you buy only grow to the size tank they are in. However, inside, their internal organs are still growing. That's why most only last a few years. In the wild the comet, which is from the carp family (that's what goldfish are - carps) can live for about 20-30 years. The fancy varieties should live about half that because they are more prone to problems due to the way they have been bred - short, round bodies, which cause swimbladder problems and make it hard to swim.
Variety in diet is important, and doesn't need to be expensive. My White clouds get a small pinch of fish flakes each day, but they also get Daphnia (a small planktonic crustacean which would be found naturally in the natural habitat of most tank fish) and brineshrimp (Artemia) once or twice a week. I am also looking at buying bloodworm for them. Most Goldfish species will eat fruit, crushed frozen peas, and cucumber in addition to their usual diet of flake or pellet food.
There is absolutely no reason to keep goldfish in cramped conditions. If you don't have room for the size tank they need, look at tropical fish instead. A small heater costs around £20 and light can easily be provided by placing a table lamp nearby. Tropical fish aren't even expensive unless you are looking at the larger fish. Most shops will sell you a shoal of 6 neon tetras, which look similar to the White Clouds for around £5-6. My own White Clouds cost £5.
They are lovely fish to watch, much more interesting to look at than goldfish and a lot easier to keep. This is a pic of 3 of mine. The one nearest the plant is called Andre.
