We have a new freshwater tank that has 2 dwarf gouramis, 3 tiger barbs and 1 tiger shark. When we first purchased the tiger barbs one had cotton mouth. We returned the fish and have treated the water with a fungus cure that contains Victoria Green B. I have been unsuccessful with removing the green color from the water and am wondering if anyone has any suggestions. I have already replaced the carbon filter and added some bio-chem zorb.

Also I am new to this & have a few other questions.
1) Two of the tiger barbs seem to stay right by where the water comes out of the filter and the other tigerbarb swims throughout the tank. Is this normal?
2) We have a 25 gallon tank with a Top Fin 30 filtration system. Do we need some sort of aerator as well?
3) Any additional recommendations to make my fish happy and the tank beautiful would help!

Seems to me the best way to remove the color from the tank is to simple do a few big water changes. Not sure about the tiger barb behavior. It doesn't sound normal. Maybe you do need more aeration. Usually when fish hang out near the top of the tank, it means they aren't getting enough oxygen. You said this was a new tank. Has it finished cycling? Do you know what the ammonia, nitrate and nitrite levels are in your tank?

hanging at the filter means they are needing more oxygen (by filters, where the water comes out of, is the richest area for oxygen in the tank unless there is aeration)

and yes, the more aeration the better - one of the main reasons I can go without changing water in the tank for one full month is because I have enough aeration breaking at the water surface which provides plenty oxygen and rids the tank of ammonia

give the tank a good 2-3 weeks to finish cycling, after, when the ammonia and nitrite are zero and nitrate hangs between 20-40 ppm, the fish will be better off

one other tip, the cooler the water the more oxygen, so you can bring the temperature down to about 76-78

(by the way, do not attempt to change water once a month - you should water change 25-30% of the water each week)

let us know how it goes

Either air stones or a powerhead, i would go with a bubbler and airstones, only problem is it is kinda loud, (i took all mine out and it is heavenly quiet now!)

Meanwhile, don't be tempted to add new fish to the tank until it has finished cycling. Keep testing your water as you go through the cycling process and do water changes as needed to keep the ammonia down.

I don't know why people say not to do water changes while you are cycling. It defies logic. I have heard the concern that doing water changes will remove the beneficial bacteria from the water, but this is not true. Most of the bacteria that you are trying to grow will be in the filter, with some in the gravel as well, but almost none will be in the water column. Doing water changes while you are cycling your tank is crucial. Until the cycle is finished, there is no other way of removing toxic chemicals from your tank other than physically removing them by way of water changes. I'm a little bit incredulous that your ammonia levels are safe. A horrible odor usually indicates that they are not. What did your test kit say your ammonia was at? But in any case, tank water should not have a horrible odor. Something is not right. I'd recommend a big water change.