As the title sugests, would it be OK to put a pair of dwarf gouramis in with a mature pair of 3 spot gouramis and a betta? The tank is a 4ft, heavily planted, and also contains neons, clown loaches, glass catfish and panda corys.
Cheers.
I would have to say that it is a bad combination. A male betta, with all its fancy finnage, is no match for an aggressive male gourami. The three spots are several times larger and much faster swimmers. Even the dwarf gouramis are faster and have larger bodies than a male betta.
Let me illustrate this with a picture of a 20 gallon tank I have now. You can see the betta and one of the gouramis near the bottom.
This tank has one male betta, three honey gouramis, and a number of dwarf corys in it. The betta is in there because I had to move it out of a specimen container that needed daily water changes, when I went away on vacation. The honey gouramis were very timid and would half bury themselves in the substrate when disturbed, so I put those tall plastic plants in there to create places for them to hide in and hoped they would be OK.
One day I was watching then from across the room and all of a sudden this little gourami darted out of the plants and attacked the betta. When the betta turned, he swam away again. This has continued with the betta occasionally being the aggressor. For whatever reason, the gouramis are no longer timid and regularly spend time swimming in the open water.
While they appear to be evenly matched, with no actual damage done to either of them, I am going to have to move the betta once I find another heated tank for him to live in. This kind of stress will do none of them any good in the long run.