fighting fish in a community tank

Yes and no. I have seen betas with Discus.... a single betta is not really aggressive to other fish (just other bettas)....

BUT that discus if not stunted already can grow up to 12" around.... 16 gallons is rather small for a single discus by itself (although not entirely small for ONLY 1 discus) but adding more fish to it will make the discus need to go to a larger tank.

 

I would say no, buy a larger tank with the money you want to spend on a discus. The fish can and prolly will coexist, the tanks just not big enough.

 

40 liters per discus is acceptable (by some, not by me) but having 1 discus in a tank is not. Discus need to be in groups of at least 4-6 minimum, unless they are a breeding pair. One discus in a small tank will fade in color quick, and not live very long.

Also, discus water must be pristine....especially for juveniles, in which the water should be changed daily, at least 40%. In a 16 gallon tank, the volume of water is such that unless the water you are putting in to do your change is exactly the same as the tank temp, you will have tempearture swings, which stress discus out alot.

 

I agree, I just did not want to get into an argument over those points. I made all of those mistakes myself (especially the 1 discus)

1 point not made is a single discus may be ok by itself..... but if you wanted to add another discus, 2, 3 or any more... that 1 discus will be the anti-social one and WILL viciously attack the other discus causing MUCH stress to them, killing new discus you try to add. Just moving them to a larger tank wont fix that problem, re-arranging wont fix it, nothing will. That 1 fish will NEVER socialize properly with the rest of the shoal.