layer of bubble on surface of tank

Question
We've had a few fish tanks before, so we kind of know what we are doing. Got a 2-gal cylindrical tank with under gravel filter for our daughter. Rinsed all parts, gravel, plant well. Let water sit for 24 hours. Got 2 gold fish. The fish are pretty unresponsive and inactive, sitting on bottom of tank. There's a layer of bubbles (not popping) covering entire surface of water. The water has a slight smell to it. We haven't treated the water with anything, as the same water always worked for our fish in the past. Any ideas? Thanks.

Answer
Hi Christine,
Sounds like a bad water pollution problem. Most likely ammonia. When new tanks are first setup they do not have a 'biofilter' established. In otherwords, good bacteria that thrive in all healthy aquariums haven't had a chance to develop yet. They take about 4-6 weeks. And these bacteria are the ones that control the toxic ammonia and nitrite levels. During their establishment time its known as 'cycling' or establising your 'biofilter'.

During this time your fish are really at risk for ammonia poisoning. I would immediately start doing 50% water changes everyday. Water changes are a life saver for fish and the key to getting them through the cycling process. Make sure when changing the water that the new water is treated with a water conditioner (that removes chlorine and chloramine) and the temp is as close to the original water as possible.

By goldfish standards, this is a very tiny tank. Goldfish produce far more waste than other species and they also outgrow most smaller aquariums as well.

You would be much better off keeping a single betta or a couple of guppies or platies in the 2-gal instead. They won't outgrow the tank and their waste load is much smaller.

I hope this helps you! Good luck!
Susan~