I have a 20 gallon high tank that has 6 zebra danios, 5 corys, and a new male dwarf gourami..Had a neon blue dwarf gourami for months and it died a week ago. Got another blue one to replace it and it died after week, yesterday morning. Just got a dwarf male gourami yesterday. It was swimming fine until i saw it when the light came on a little bit ago. Was swimming like my last gourami did before it died. He is on bottom of tank, swimming kind of sideways, and hiding in rock decoration or plastic plants. All the other fish are swimming around like they have been. I have had this tank about a year, I think. What can I do? If this one dies, I'm afraid to get another one. What other type of colorful fish can I get instead that might have better survival chance? I did a water change last Wed. I do one once a week and vacuum.