Also when she goes up for air bubbles come out of her gills. Is this normal? With the other 2 this doesn’t happen.
Gouramis are labyrinth fishes and can breath air from the atmosphere. It is common for gouramis and Bettas to take air from the surface and sometimes they have bubbles coming out under the gill covers.
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Check the water quality for ammonia, nitrite, nitrate and pH.
Do a 75% water change and gravel clean the substrate any day you have an ammonia or nitrite reading above 0ppm, or a nitrate reading above 20ppm.
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Don't add any more fish to the tanks and don't move fish around until you know what the water quality (ammonia, nitrite, nitrate, pH) is like.
If you have mollies, check the general hardness (GH). Mollies need a GH of 250+ppm and a pH above 7.0.
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).