HagenKB

New 5.5 gallon aquarium - dying fish

About two weeks ago I purchased a Hagen 5.5 gallon starter aquarium. I had about 12 small starter fish in it two weeks ago and up until yesterday I still had all twelve. All of a sudden 7 of my twelve fish died; within a couple of hours. I left to go out

About two weeks ago I purchased a Hagen 5.5 gallon starter aquarium. I had about 12 small starter fish in it two weeks ago and up until yesterday I still had all twelve. All of a sudden 7 of my twelve fish died; within a couple of hours. I left to go out
It sounds as if you are undergoing one of the most common problem new aquarists encounter when they begin. In many cases a new aquarist will overload the aquarium before it is ready to accept a normal load. This may indeed be the case here. 12 fish is quite a load for a 5.5 gallon aquarium, and when the water and all filtration is new, it is probably overloaded for sure.

I think the Basic Aquarium Guide should have been included in your set, otherwise, if you wander over the website, you will find the Basic Aquarium Guide there, either through the manuals section of the Product Information System, or from the electrical products section. In it there is a section on the Nitrogen Cycle, which after about 10 - 15 days the fish will create a high enough concentration of ammonia to cause stress or kill them. It takes about a month to six weeks to mature the biological filter and allow it time to grow a large enough population of beneficial bacteria to remove all the ammonia and its by-product nitrite.

Use of Cycle will speed up the process quite a bit, but there is still production and if the aquarium is carrying high loads, there may not be enough of a safety cushion to keep the fish alive through the maturation period. You don't mention the types of fish, but the rule of thumb for a 5.5 tank would be 11" of fish when fully matured, and 5.5 (or about an inch a gallon) when starting out the aquarium. I would be willing to be you were on the high side of these numbers.

I am sorry you are having trouble in the very beginning, but in the long run the learning you are doing right now will help to make you a much better aquarist.

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