Are you thinking of creating a community aquarium? Community fish are fish that can be kept in the same aquarium without causing issues with its tankmates. Often times, community aquariums are colorful, boasting a variety of fish, plants and decor. Community tanks are very rewarding if all your fish are cohabitating peacefully. However, it’s a different story if your fish are not getting along and attacking each other! You need to choose the right fish for your community aquarium. You don’t want to make the mistake and choose fish that are aggressive and territorial. Or fish that can grow too large that it’s not suitable in a community tank. That’s why it’s important to know which are the worst fish for community tanks. Below are 12 worst freshwater fish for community tanks.
12 Worst Fish for Community Tanks
1. Jack Dempsey (Cichlasoma octofasciatum)
Jack Dempsey are cichlids that should not be kept in community tanks. First of all, Jack Dempsey can grow quite large up to 8 inches long! It is commonly sold as juveniles in pet stores as part of a mixed cichlids variety for cichlid community tanks. Beware, Jack Dempsey can get aggressive and will bully other fish if kept in a community tank. If you want a Jack Dempsey, keep it in a species only aquarium or with other large, tough cichlids.
| Jack Dempsey Cichlid | |
|---|---|
| Family | Cichlidae |
| Size | 8 inches |
| Food | Omnivorous |
| Temperature | 72-77 F |
| Why It’s Bad in Community Tank | Gets too big and too aggressive |
2. Green Pufferfish (Tetraodon fluviatilis)
Green Pufferfish should not be kept in community tanks. It should only be in a species only tank because pufferfish are very aggressive. They will nip fins, attack and kill other fish in the community tank. Aside from being aggressive, green pufferfish require brackish water which is not compatible with the water in most community tanks.
| Green Pufferfish | |
|---|---|
| Family | Tetraodontidae |
| Size | 6.75 inches (17 cm) |
| Food | Omnivorous |
| Temperature | 72-82 F (24-28C) |
| Why It’s Bad in Community Tank | Extremely aggressive |
3. Red Tailed Black Shark (Epalzeorhynchus bicolor)
Red Tailed Black Shark should not be kept in community tanks with other fish. Both male and female Red Tailed Black Shark are extremely territorial and will wreak havoc in community tanks. Red Tailed Black Shark are loners and will even be aggressive towards its own species!
| Red Tailed Black Shark | |
|---|---|
| Family | Cypirinae |
| Size | 4.75 inches (12 cm) |
| Food | Omnivorous |
| Temperature | 72-79 F (22-26C) |
| Why It’s Bad in Community Tank | Aggressive |
4. Red Devil (Amphilophus labiatus)
Red Devil is one of the worst community fish you can add to your community aquarium. It is an extremely aggressive and territorial fish. If kept in a community aquarium, it will definitely eat up everything! I don’t recommend Red Devil in your community tank.
| Red Devil Cichlid | |
|---|---|
| Family | Cichlidae |
| Size | 10 inches |
| Food | Omnivorous |
| Temperature | 75-79 F |
| Why It’s Bad in Community Tank | Extremely aggressive |
5. Tinfoil Barb (Barbonymus schwanenfeldii)
Tinfoil Barbs should not be added in community tanks. They are commonly sold at pet stores as small juveniles and often kept in community tanks. However, most people who buy Tinfoil Barbs don’t realize they can grow up to 14 inches long! Imagine a school of fish where each fish is 14 inches long! They will quickly outgrow the community tank! You need really large aquariums to keep Tinfoil Barbs. Don’t be fooled by its small, juvenile size. Tinfoil Barbs are one of the worst fish you can add to a community tank.
| Tinfoil Barb | |
|---|---|
| Family | Cyprinidae |
| Size | 14 inches |
| Food | Omnivorous |
| Temperature | 72-77 F |
| Why It’s Bad in Community Tank | Can Grow Really Big |
6. Discus (Symphysodon aequifasciatus)
Discus fish should not be kept in community tanks. Discus requires soft, acidic water which are not compatible with most community fish. If you want to keep discus, you should keep them in a discus-only aquarium. Discus are generally peaceful fish but will get very territorial when breeding. I don’t recommend discus in community tanks.
| Discus | |
|---|---|
| Family | Cichlidae |
| Size | 6 inches |
| Food | Carnovirous |
| Temperature | 79-86 F |
| Why It’s Bad in Community Tank | Requires soft, acidic water. Aggressive when breeding. |
7. Sucking Loach (Gyrinocheilus aymonieri)
Sucking Loaches are freshwater fish that should not be kept in community tanks. They are sold as juveniles and often added into community tanks as the bottom-dweller, algae-eater fish. However, Sucking Loaches can grow really big, up to 11 inches long! They are also very territorial and aggressive towards tankmates. Sucking Loaches can become a problem in community tanks.
| Sucking Loach | |
|---|---|
| Family | Gyrinocheilidae |
| Size | 11 inches |
| Food | Herbivorous |
| Temperature | 77-82 F |
| Why It’s Bad in Community Tank | Grows Really Big. Aggressive and Territorial. |
8. Red Snakehead (Channa micropeltes)
Red Snakeheads is a freshwater fish that should not be kept in community tanks. They are sold as small juveniles but can grow really big to 39 inches long! Red Snakeheads are carnivores and if kept in a community tank will soon eat up all the tankmates!
| Red Snakehead | |
|---|---|
| Family | Channidae |
| Size | 39 inches |
| Food | Carnivorous |
| Temperature | 77-82 F |
| Why It’s Bad in Community Tank | Grows Really Big. Aggressive Carnivore. |
9. Oscar (Astronotus ocellatus)
Oscars should not be kept in community tanks. Oscars are usually sold as juveniles and often times, pet stores don’t disclose the true adult size. Oscars can grow really large- up to 13 inches long. They are large carnivores. If kept in a community tank, Oscars will eat up all the smaller tankmates. Large carnivores are never a good idea in community tanks! Keep Oscars in a large, dedicated aquarium that is at least 50 gallons.
| Oscar Cichlid | |
|---|---|
| Family | Cichlidae |
| Size | 13 inches |
| Food | Carnivorous |
| Temperature | 72-77 F |
| Why It’s Bad in Community Tank | Grows too Big. Carnivore, will eat smaller fish. |
10. Tiger Barb (Barbus tetrazona)
Tiger Barbs should not be kept in community tanks. They have a reputation for being fin nippers. Avoid keeping tiger barbs with long fin species like Angelfish and guppies. They should be kept in groups of 6 or more to decrease aggression.
| Tiger Barb | |
|---|---|
| Family | Cyprinidae |
| Size | 2.75 inches (7 cm) |
| Food | Omnivorous |
| Temperature | 72-79 F (22-26C) |
| Why It’s Bad in Community Tank | Fin Nippers |
11. Silver Shark (Balantiocheilus melanopterus)
Silver sharks or Bala Sharks should not be kept in community tanks. They are sold as juveniles and often times, pet stores fail to disclose the adult size of silver sharks. Silver sharks can grow really big, up to 14 inches long! They will quickly outgrow community tanks and become a predator, eating up all the small tankmates.
| Silver Shark (Bala Shark) | |
|---|---|
| Family | Cyprinidae |
| Size | 14 inches (35 cm) |
| Food | Herbivorous |
| Temperature | 72-82 F (24-28C) |
| Why It’s Bad in Community Tank | Too Large. Will Eat Smaller Fish. |
12. Siamese Fighting Fish (Betta splendens)
Siamese Fighting Fish or Bettas should not be kept in community tanks. They are loner fish, ideally in aquariums with no other fish. Male Bettas are aggressive towards other Bettas. Male Bettas will fight to the death (hence the name fighting fish!) and male Bettas will become extremely aggressive towards female Bettas after spawning. Female Bettas are less aggressive and can be kept together in a female Betta-only tank. Sometimes people keep one Betta in their community tank but you risk getting its fins nipped by tankmates. Overall, I think it’s not a good idea to keep Bettas in community tanks.
| Siamese Fighting Fish | |
|---|---|
| Family | Belontiidae |
| Size | 2.5 inches (6 cm) |
| Food | Carnivorous |
| Temperature | 72-82 F (24-28C) |
| Why It’s Bad in Community Tank | Aggressive. Fins will get nipped. |
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