Aquarium Problem

[AberdeenAl]

We have had an aquarium for years - tropical fresh water fish. Last week there was quite a build-up of algae on the glass and on the gravel so I cleaned it up with the usual scrub brush. Yesterday we had 6 dead fish and today another 2. These are the first losses for more than a year. The water is now really cloudy and looks very unhealthy. We have not introduced any new fish or plants and are still using the same fish food.

Could I have disturbed the natural balance of the tank somehow by my cleaning? I have done this in the past a few times but never with this catastrophic effect. Appreciate any advice thanks.

[boxtops]

do you think there could have been something toxic to the fish on the scrub brush (e.g. detergent)?

[Tuvok]

Test your water and perhaps do a water change.

[grasscarp]

I once cleaned aquarium stones with bleach. All the fish died. Big mistake.

[AberdeenAl]

Definitely no contamination with scrub brush and have never used bleach could come in contact with tank. Any other ideas?

[wildwood]

What type of filtration do you have? I suspect that by cleaning the gravel you've also remove the beneficial bacteria and now have an ammonia spike.

Test the water Tuvok said, if you can't test it yourself take a small amount to a pet/fish shop, any decent one should test the water for free.