dead dwarf gourami

Question
I purchased 2 dwarf gouramis a week ago and they are in a 20 gallon tank with a orange colored gourami, 3 neons, 5 guppies, and 2 chinese algae eaters.  This morning the smaller dwarf gourami started flipping through the water and even jumped up out of the water at the top and back down and then floated to the bottom laying on its side. Probably 5 seconds later he jerked up and swam to a plant and then back out and floated back to the bottom and died right away. It acted like it was having a seizure.  I checked my water and everything was ok. What could have happened to it?

Answer
Hi.
Firstly, Algae Eaters are not appropriate for a tank of that size. You should rehome them if possible, or they will die as they grow. Also, guppies and tetras do not fair well together, so I would either rehome the tetras, or the guppies. Also, tetras prefer to be in groups of 6 or more.
The gourami most likely died of stress, so check the water stats again. Are the nitrite and ammonia both 0.0? Even 0.1 is harmful. Is the nitrate under 30ppm? Live plants can help lower it. Is the pH between 6.5 and 7.2? Things need to be perfect, or they will suffer.
Good luck,
Kathryn