My fish keep on dying!

Question
Hey Nathan -
I've got a serious problem with my fish tank but I have no
idea what is wrong. I've got a fairly small tank, equipped
with a filter, an air pump, a light, foam (for the filter)
and those little stones that assist with the filter. I've
also got gravel. In the past, the fish I keep only seem to
last a week or two (a month at the most). I went to my
local fish shop and they said, since my fish tank is
upstairs and gets hot quite easily, I should buy an air
pump due to the lack of oxygen. So, I completely emptied my
fish tank, cleaned it, refilled it with conditioned water,
got the filter going again, and the air pump (with a
stone), and put a pinch of fish food in the tank to get the
cycle going again. After a week, I checked the pH, ammonia,
nitrate and nitrite and everything was normal except for
the pH, which was high. I purchased some pH 'low' which
brought the level back to normal. After two weeks from when
I completely reset my fish tank, I purchased a comet gold
fish. I fed it a pinch of fish food a day, disposing of the
left over food. After a week, it died, like all the others.
Can you help me?

Answer
Hi Georgia,

What size is your tank? You mentioned that it was rather small. Comet Goldfish need a very large aquarium, of at least 30 gallons if you plan on keeping them for their whole lives. Don't be fooled by their small size, because Comets can grow up to 24" (60cm) when fully grown. They are among the largest of all Goldfish, although they are quite tiny when you buy them. They will die prematurely in a small aquarium, because the toxin levels in a small tank will become poisonous, killing your fish.

You must get a larger tank and a filter suitable for that tank size. Filters are necessary for all fish, and without a filter, there is a 100% chance that a fish will die. (Good thing you have a filter for your current tank, because MANY people keep Goldfish in bowls!) If you cannot get a larger tank, you will have to give your Comet Goldfish away.

For now, until you get a larger tank/give it away, perform 20% water changes in your tank daily, replacing with fresh water, to maximize your fish's survival.

Your feeding routine seems great!

If you have any more questions, don't hesitate to ask!

Good Luck, and Happy Fishkeeping!