Please refrain from trying to get around the profanity filter of this site.
DEAN BARNES, sorry about all your fish
Like the others said, we need more information. Look at this post and answer these questions:
http://www.aquariumadvice.com/viewtopic.php?t=33947
Here is another good article to read:
http://www.aquariumadvice.com/showquestion.php?faq=2&fldAuto=21
My first thought is a bacterial infection. Columnaris often causes the swollen or "growth"appearance of the mouth, and antibiotics may be necessary to treat.
Some other thoughts: As mentioned, two male bettas can never live together. A male and a female can be put together briefly to breed; they can't live as tankmates. A betta and a gourami probably won't get along. They may, however, if the tank is big enough -- say, 55 gallons. A group of tetras may end up ganging up on, and nipping, the fins of a slow-moving betta.
It seems like you may have had an uncycled tank, some incompatability issues, and one or more fish that spread an infection. How many of the fish do you still have? Read up on the nitrogen cycle, with the article I linked and some google searches. Consider the compatibility of new fish and do some research. Here are some good sites for fish profiles:
http://www.liveaquaria.com/product/categ.cfm?pCatId=830
http://fish.mongabay.com/fish.htm
It's a good idea to set up a
QT tank to isolate new fish before you introduce them to the main tank. A
QT doesn't have to be fancy or expensive. It can be a rubbermaid container, with a heater, sponge filter, and a few plastic plants or
pvc pipes/elbows for hiding places. If the new fish seem to be sick, they can be treated in the
QT tank without affecting the fish in the main tank.
