Bettas and Otocinclus Catfish can’t be kept together without careful preparations.
In this article, we’ll tell you everything you need to know about how to prepare your aquarium so your Bettas and your Otocinclus Catfish can peacefully coexist.
But first, we’ll tell you a story about what can happen when you don’t take appropriate precautions for keeping these fish in the same aquarium.
Bettas and Otocinclus Catfish Don’t Do Well in Close Quarters
Four-year-old Samantha wanted one thing for her birthday: A trip to the “fish store.”
Her accommodating grandparents took her to buy a 55-gallon aquarium with filters, heaters, lights, and plants.
Samantha picked out two fish for her first aquatic pets. One was the biggest Betta in the Betta tank.
She named the Betta Betty. Then Samantha picked out the smallest Otocinclus Catfish in the store.
She named it after a word she had just learned for cats, Feline.
Samantha and her grandparents got to her parents’ house close to bedtime. Samantha’s parents decided they would set up the aquarium the next day.
In the meantime, they would let Betty the Betta and Feline the Otocinclus Catfish spend the night in a hand-me-down goldfish bowl.
Samantha woke up early the next morning to spend time with her fish, but when she went to the den, where they had left the fish for the night, Betty was there, but Feline was AWOL.
Samantha ran into her parents’ bedroom crying that her fish was gone.
Samantha’s parents checked the fishbowl. Feline was indeed gone. Betty seemed even larger than she had been in the fish shop.
Samantha’s parents told her that Feline must have decided to go out and play with some other catfish.
Left together in a small space with no plants or aquarium toys (and not fed the day before), Bettas and Otocinclus Catfish are not good tank mates.
But you can prepare your aquarium so your Bettas and Otocinclus Catfish can live together peacefully.
Bettas and Otocinclus Catfish Prefer Similar Water Conditions
One obstacle to keeping Bettas and Otocinclus Catfish in the same tank would be different requirements in water conditions.
Fortunately, with Bettas and Otocinclus Catfish that is not a problem.
Bettas and Otocinclus Catfish prefer about the same temperatures and about the same water pH.
Bettas prefer temperatures between 76° and 80° F (24° and 27° C).
Otocinclus Catfish can tolerate slightly cooler temperatures, between 72° and 80° F (22° and 27° C). Keeping your aquarium at a constant 78° F (26° C) will suit both kinds of fish.
Bettas and Otocinclus Catfish also like their water at the same pH, a slightly acidic 6.8 to 6.9
And like any other kind of fish you can keep in your aquarium, they need nitrite and ammonia levels (reflecting the amount of waste matter they leave in the tank) to be as close to zero as possible, preferably no more than 20 ppm.
But Bettas and Otocinclus Catfish prefer different amounts of current.
Bettas Like Still Water, but Otocinclus Catfish Like a Strong Current
Bettas have beautiful fins, but they aren’t very strong swimmers. Their fins are so long that they can’t steer very well in strong currents.
Bettas prefer slow-moving or still water. If you had nothing but Bettas in your tank, you might even omit the water filter to give them the still water they prefer for swimming.
Otocinclus Catfish, on the other hand, prefer moving water.
They like to graze on the kinds of algae that cling to plants, rocks, and driftwood in a strong current that keeps the water free of pond scum.
In their native streams in South America, Otocinclus Catfish live together in rocky shoals in the bottom of fast-moving streams.
They feel more secure when they are with other Otocinclus Catfish. They are happier when they have places to hide out of the mainstream at higher levels.
How Can You Set Up Your Tank for Both Still and Moving Water?
Balancing the Bettas’ need for still water and the Otocinclus Catfish’s need for moving water is the hardest part of setting up an aquarium to house both species.
The best way to do this is to make sure you have a tank that is 20 gallons (80 liters) are larger, with a filter, and with decorations that create ebbs and eddies that give some parts of the tank still water and other parts of the tank flowing water.
Place plants and decorations in front of the filter that is providing water flow.
Put them out sparsely immediately in front of the filter to give your Otos the current they enjoy.
Put them out densely farther away from the filter to create still water for your Bettas.
There are several ways to set your filters to do this:
- Place an undergravel filter in one corner of the tank with its air pump outside the aquarium. Water current is generated at the bottom of the tank, where your Otocinclus Catfish will prefer to hang out. You need to keep the pump itself at water level, so water won’t flow back into it if the power goes out. This is especially important if the pump hangs on the back of the tank.
- Canister filters can’t be submerged because they fit on the back of the tank, because they are designed that way. They aren’t a good choice when you are keeping Bettas.
- Corner filters, the kind you keep in place with suction cups, are OK for Bettas, but you need to keep them as close to the substrate as possible.
Feeding Bettas and Otos in the Same Tank
Bettas and Otocinclus Catfish don’t eat the same food.
Bettas are primarily meat-eaters. Otos primarily eat plants.
Bettas are opportunistic eaters, which means that they will feed on the food you are giving your Otocinclus Catfish if they don’t get their own.
Fortunately, Otos only need to be fed once a day, while Bettas need to be fed twice a day.
If you are careful to keep on your feeding schedule, your Bettas won’t be interested in the food you are giving your Otos.
Bettas like high-quality food pellets, mosquito larvae, and Daphnia (water fleas). In the wild, they would catch mosquito larvae and water fleas at the surface.
Otos prefer algae tablets (which you can buy at pet stores or online) and an occasional vegetable, like blanched cabbage or zucchini.
Otos will also feed on any algae that grows on the driftwood or decorations in your tank.
You shouldn’t leave any uneaten vegetables in the tank for more than 24 hours, so they won’t decay.
Managing Aggression in Bettas
Bettas are naturally aggressive. After all, they survive by hunting for tiny insects like water fleas. They naturally dart and bite.
Otos are naturally peaceful. They feed on plants growing at the bottom of their habitat. They depend on their spines and their rocky homes for protection.
Not all Bettas will make good tank mates for Otos. But there is a simple rule that will help you avoid trouble:
Always add Otos to a Betta tank, not Bettas to an Oto tank.
If you have had a peaceful, well-fed Betta (or Bettas) for several weeks, and the tank is set up with a gravel substrate, a filter at the bottom of the tank (to encourage the Bettas to stay at the top), and numerous decorations at a distance from the corner where you have the filter, then it’s OK to try adding Otos.
You will want to buy Otos that look healthy and active.
Unlike North American catfish, healthy isn’t ever gray. They are olive, brown, black or white.
You should quarantine Otos in their own tank or at least a week when you get them home, before you put them with other fish.
You need to pay attention to their bellies. If they are bloated, they may have a bacterial infection that they can spread to other fish.
If their bellies are caved in, they may not have been fed on their trip from South America to the fish store, and won’t have the strength to deal with Bettas.
Once you are sure your Otos are healthy, then you can add them to their corner next to the filter at the bottom of the tank.
It is especially important for the next few days to feed your Bettas on schedule to keep them from fighting with their new tank mates.
Bettas and Otocinclus Catfish aren’t ideal tank mates, but adding Otos (preferably more than one at a time) to your Betta tank will keep algae problems to a minimum.
The Otos will also keep your Betas from getting bored. Just be prepared for some losses if you don’t take careful steps to prepare for providing both fish a happy home.
A Frequently Asked Question
Q. Are there any other kinds of fish that can live in the same aquarium with Bettas?
A. There are over two dozen kinds of fish and aquatic creatures that can coexist with Bettas, provided the tank is large enough. Here is a list for easy reference.
- Harlequin Rasboras
- Lambchop Rasboras
- Ember Tetras
- Guppies (Under Certain Conditions)
- Platies
- Dwarf Rasboras
- Pygmy Corys
- Bronze Corys
- Endlers Livebearers
- Mosquito Rasbora
- Dwarf Loach
- Zebra Danios
- Rummy Nose Tetras
- Cardinal Tetras
- Neon Tetras
- Black Neon Tetras
- Mollies
- Scissortail Rasboras
- Assassin Snails
- Amano Shrimp
- Redtail Sharks
- Glass Catfish
- Malaysian Trumpet Snails
- Ramshorn Snails
- Mystery Snails
- Nerite Snails
- Ghost Shrimp
- Cherry Shrimp
- Dwarf Crayfish
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