Some fish species is not good for a community tank. They will disturb and damage the peaceful in the tank; moreover, they will eat other fish. Uniquely, they also attack same species fish even their brother. You have better to quarantine the fish in one tank.
The fish that is better for solitaire tanks i.e.:
1. Betta Fish (Betta Spelendens)
Betta is most beautiful fish in the world. Betta fish is also an aggressive fish that could attack any fish include their brother. You should remove the fish when they are still small. They could fight since they are small. A breeder told me that he just produced one fry in one breeding. He had forgotten to separate the fry and the fry fought each other.
2. Wolf Fish or Tiger Fish (Hoplias Malabarincus)
Wolf fish is a bad horrible fish. Wolf Fish is also called Piranha eaters. They are recorded as piranha eater. They are not suitable for community tank. They will attack any fish include same species fish.
3. Louhan
Louhan is hydride fish that has beautiful color. They have aggressive behavior like their ancestors. They will attack any fish include a female Louhan, if the male does not like the female. If, on the other hand, the male like the female, they will become a pair. They will produce some fry later.
If you like care a solitaire fish in a single tank; you can care these fishes above. On the other hand, the single tank could make the owner bored. You just could see one fish in large tanks.
