Hi, so i had a 14 litre tank with 8 baby goldfish that my dad gave me becaouse they were way to small to put in his koi pond outside, now they have grown abit i have bought a 30ish litre hexagen tall tank, i don't plan on keeping the goldfish as im giving them out to friends and family but my point is can i cycle it fully with the golfish(water changes daily) and then when i have got rid of the all the goldfish put a heater in overnight and get tropical, in other words can i cycle it with golfish then change to tropical overnight adding a heater?
Thanks James
You can cycle with goldfish and then add a heater to slowly bring the temperature up. This is possible, from a biological standpoint, as the bacteria will adapt to the temperature.
HOWEVER
You need to consider two things, and these a very, very important for your pets.
1) If you cycle with the goldfish (especially that number of goldfish in such a small tank) you will have major problems. Unless you are doing 90% water changes 3-4 times a day
without fail you are going to find the tank gets very toxic for the fish. You talk about using the fish to cycle - why? All that does is mean you have to do lots of water changes to keep the fish safe and you are putting the fish at massive risk of getting poisoned by the ammonia and nitrite in the tank? Why do that to your fish and why put yourself through so much work? If you said you had 1-2 tiny fish and you wanted to cycle with those, ti would be easier and safer but you are talking about goldfish whcih grow fast and produce a lot of waste, which means the ammonia will build up veru quickly. What about a fishless cycle? Easier on you (no water changes) and doesn't put a risk on your pets.
Here is a link to general cycling info.
2) Goldfish should not be in such a small tank, let alone 8 of them!! Goldfish have huge potential for growth and one of the most common causes of goldfish death are ammonia poisoning (from people keeping them in small tanks and bowls without adequate filtration) and from stunted growth (from people keeping them in small tanks). A single fancy goldfish (which are smaller than commons/comets/pond goldfish) would need 20 gallons just to make sure they didn't get stunted as a baby and then they'd need 25-30 gallons as an adult. A pair would need 30-40 gallons, etc. You are talking about keeping 8 in a 14-30 litre tank??? These fish are going to get very sick. You say you are giving them away but you want to cycle the tank with them first - no, please re-home them NOW. They need to get into decent sized tanks as soon as possible, not after a couple of months when your tank is cycled. You also have a responsibility to ensure that these fish go into adequate homes, not small tanks or bowls. If they are common, comet or other single-tailed, straight bodied goldfish they need to be in a large pond unless you can find someone with a properly set up goldfish tank that is lightly stocked and over 6 foot long. Yep, these guys get BIG. If they are fancy types (google fancy goldfish if you're not sure) then as I said, a single fish would need 20 gallons to start with to make sure they had enough space to reach their adult size of around 6-8 inches. All goldfish should be kept in pairs or trios so really, you're looking at finding 2-4 homes for them each with a large coolwater goldfish tank of at least 35-40 gallons.
Please, please think of these fish. Your father was very irresponsible for giving you these fish and you both should have done some proper research into their care.
Also, with the best will in the world, putting 8 goldfish, however small, in 14 litres (or even 30) is poisoning them...not deliberately, I know, but the end result is the same...
