A common misconception held by people who are just getting started with keeping fish is that you can put any two kinds of fish together and they will get along with each other.
This is not true, especially when one of the two kinds of fish is a Betta.
Fish are like every other kind of pet in that some will get along, while others will annoy, harm, or even kill each other.
You should always do some online research before putting two or more kinds of fish together in the same tank, especially if one of those kinds of fish is Bettas.
Plecos (short for Plecostomus), however, rank high on a shortlist of fish that can coexist with Bettas.
Plecos and Bettas can get along for reasons that aren’t hard to understand.
Why Plecos and Bettas Make Tolerant Tank Mates
Plecos are peaceful and shy.
They feed on algae that grow on plants and decorations in their aquarium, supplemented by algae tablets and blanched vegetables you feed them several times a week.
They may eat some of the food your Bettas miss when it lands on the bottom of the tank, but they won’t swim up to the surface to join the feeding frenzy when you feed your Bettas twice a day.
Bettas eat water fleas (Daphnia), mosquito larvae, and fish pellets made for meat-eating fish. In nature, they have to be aggressive about feeding.
Water fleas and mosquito larvae can easily escape if the Betta isn’t quick to catch them.
There aren’t always enough water fleas and mosquito larvae to go around, so Bettas may shove each other out of the way to catch their meal.
And because water fleas and mosquito larvae are found at the top of the still water in which Bettas live, Bettas claim the water in the top of the aquarium as their own.
Plecos aren’t competitive with each other about the algae they eat. They swim together for protection at the bottom of the streams where they live.
It also helps that Plecos have armor-like plates called scutes on the top of their body (their underbelly is not protected by them), the part of the body that is exposed to the Bettas that like to swim above them.
It also helps that Plecos have a lower body temperature and less color than Bettas.
Plecos live at the bottom of the tank, where the water is a degree or two cooler than at the surface of the tank.
Bettas have infrared vision, that is, they can see heat, but a Pleco will not be as noticeable to them as another Betta.
Plecos are also less colorful than other fish. Bettas can see red, blue, and yellow, but these colors are absent in the scales of a Pleco.
Other Reasons Plecos and Bettas Get Along Well in the Same Aquarium
Another reason Plecos and Bettas get along so well is that they like the same water conditions.
Plecos and Bettas have overlapping requirements for water temperature and water pH.
In nature, Bettas swim at the top of still water that is warmed by the sun.
They like their water to be at temperatures between 76° and 80° F (24° and 27° C).
In nature, Plecos live at lower, cooler, but still-warm depths. They can do well at slightly cooler temperatures, between 72° and 80° F (22° and 27° C).
Striking a compromise by keeping your aquarium at a constant 78° F (26° C) will suit both kinds of fish.
Bettas and Plecos like their water slightly acidic, at a pH of 6.8 to 6.9.
Plecos and Bettas prefer good water quality, with nitrates and ammonia as close to zero as possible, preferably no more than 20 ppm.
But Plecos and Bettas prefer different amounts of current.
Plecos Like a Strong Current, While Bettas Prefer Still Water
In nature, Bettas don’t like anything that interferes with their nabbing small crustaceans, and insect larvae for the next meal.
They don’t want to have to try to catch a moving, live bug that is also be carried by a water current.
Moreover, despite having beautiful fins, Bettas aren’t very good swimmers.
They just can’t keep up with strong currents rolling both over and under them.
Plecos are bottom feeders. They don’t have to deal with water current underneath their bodies.
Their mouths provide the suction they need to eat algae and stay stable while strong current rolls over them.
The kinds of algae they eat thrive in moving, oxygenated, clear water that allows sunlight to reach the bottom of the stream.
Creating an aquarium that has still water for your Bettas and moving water for your Plecos is the hardest part of setting up an environment that is friendly to both species of fish.
You will need a sizable tank, at least 20 gallons (80 liters, and preferably 55 gallons (capacity equal to a 55-gallon drum—not that you should ever keep fish in a 55-gallon drum, or 80 liters).
And while you might not use a filtration system at all if you only had Bettas in your aquarium, you will need a filtration system to produce current for your Plecos.
Here’s the most important thing to remember about setting up the filtration system for a tank that will hold both Plecos and Bettas:
Place the filtration system as low in the tank as possible.
In fact, your best choice for an aquarium that holds both Plecos and Bettas is to have an under gravel filter in one corner of the tank, with its air pump completely outside the aquarium.
An under gravel filter will create a current at the bottom of the tank, where your Plecos live.
Give your Plecos a corner of the aquarium they can use as their own by placing any plants, driftwood, or decorations a few inches to a foot away from the filter.
Let your Bettas occupy the other side of the plants and decoration blocking the current.
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 Plecos the current they enjoy.
Put them out densely farther away from the filter to create still water for your Bettas.
Corner pumps, the kind you attach to your aquarium with suction cups, also work, but you need to keep them as close to the bottom of the tank as possible.
Place the pump itself above water level, so the water level in the tank won’t fall if the power goes out.
It’s Easy to Feed Plecos and Bettas in the Same Tank
Feeding time is easy when you have Plecos and Bettas at the same time, because they don’t eat the same food and they don’t eat on the same schedule.
Plecos are primarily vegetarian. They sometimes eat a few freshwater shrimp and clams they find at the bottom of their stream.
Bettas are carnivores. You will be feeding them water fleas, mosquito larvae, and fish pellets.
Plecos and Bettas eat on different schedules. You feed your Bettas twice a day, but you feed your Plecos just five or six times a week.
There aren’t any problems with feeding Plecos and Bettas in the ae tank as long as you feed your Bettas on schedule, so they won’t be tempted to swim down and try to feed on the Plecos.
Plecos won’t have any interest in the Betta food and Bettas won’t have any interest in Pleco food if all the fish get enough.
Add Plecos to a Betta Tank (Not the Other Way Round)
When you are putting Plecos and Bettas into the same tank, you always place Plecos into an established tank of Bettas, rather than the other way around.
This gives you an opportunity to observe the Bettas before you expose them to other fish.
If your Bettas seem happy in their tank, not fighting very often, then it’s OK to add Plecos.
But if you place a new Betta into a tank of Plecos, it is likely to be aggressive to stake out its territory.
Are There Any Other Fish That Are Compatible with Bettas?
If Plecos don’t work out as an addition to your Betta tank, there are other species of fish that may:
- Harlequin Rasboras live with Bettas in the wild. As long as you add at least six Harlequin Rasboras to the tank at a time, they should be compatible.
- Kuhli Loaches look like eels. They could overpower your Bettas, but they won’t. They will spend most of their time at the bottom of their tank alone.
- Neon Tetras are smaller but faster than Bettas. Keep six or more Neon Tetras together to protect each other.
- Corydora Catfish require care similar to the care you give Plecos, but they are a social fish. Put two or three in your tank with your Bettas.
Are There Any Fish that Never Get Along with Bettas?
Goldfish and Bettas don’t mix.
Bettas like clear, pristine water. Goldfish are messy. Also, Goldfish prefer lower temperatures.
It’s not a good idea to keep two Bettas together in any tank less than 55 gallons (200 liters). They will usually attack each other.
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