Bugs eating our fish kind of like ants

Question
Hi Karen,

We have a freshwater tank and there seem to be bugs floating on the surface and some bugs in the gravel. They are brownish and kind of look like eggs. I noticed today that there was one fish at the bottom of the tank and it was being devoured by these bugs like ants. Any ideas on this? I really don't want the fish to be killed. Your help is greatly appreciated.

Thanks!
Lydia

Answer
Hi Lydia,
There are many kinds of insects/crustaceans that can invade our aquariums and be labeled as pests indeed.

Fortunately though, most all are harmless scavengers and although I'm not confirming this -- I am thinking the fish died from some other cause and the bugs took advantage of the available food.

The presence of small bugs in the aquarium could be the result of one or more critters getting into the tank from the outdoors and then quickly causing the infestation. Or sometimes it can mean the aquarium is not receiving enough maintenance. For example, since many are scavengers living off whatever waste they can find...large numbers would mean there is a high enough food supply for them to maintain such a large population. The simple answer to that is to do several 30-50% water changes/gravel vacuuming to remove both the bugs and excess waste. Once their food supply is depleted their population cannot sustain itself.

So what I would recommend you try is to do a 30% water change and using your gravel vacuum to siphon up debris in the gravel and as many bugs as you can. Always remember replacement water should be treated with water conditioner and the temp should be equal to or just a bit warmer than your tank's temp.

You may have to repeat these daily water changes for a while but it is the best option with the fishes well-being in mind. Its much much safer for the fish than treating the water with a chemical to kill of the bugs.

How big are the bugs by the way? Could you get any pics of them?

I do hope this helps and best of luck!
Karen~