However, properly acclimated plecos can learn to tolerate or even enjoy the presence of tankmates of the same species. With proper measures, an experienced aquarist can successfully keep several plecostomus in the same tank.
Instructions
Verify that your tank is large enough to accommodate more than one pleco. Plecos can grow to 20 inches or more and require at least 55 gallons of space. Pleco fry, very young fish, require at least 10 gallons of water per pleco; two young plecos could temporarily share a 20-gallon aquarium. Overcrowded plecostomus will die of nitrate poisoning and ammonia buildup due to their high waste output.
Create hiding spaces throughout the aquarium, including caves, plants and rocky outcroppings. Plecos are extremely territorial; they will only coexist peacefully if each fish has his own established domain. If the new pleco has places where she can seek refuge from rivals, she is more likely to survive and thrive in her new environment.
Quarantine the new fish in an isolation tank for the first week after purchasing her. Do not introduce her to other plecos if she shows any symptoms of illness, such as sluggishness, white spots or patches, rotting fins or unusual behavior.
Float the new pleco in a plastic bag for one to two hours before releasing him freely into the tank. This gives him time to adjust to the temperature and lighting of the tank and allows other plecostomus the opportunity to observe him.
Release the pleco into the tank and monitor the behavior of the other plecos. They may attack her immediately; if she is unable to hide or defend herself, remove her from the aquarium and try again in a few hours. She will most likely go about staking out territory within her first week in the new tank. Monitor the behavior of all the plecos and note any aggression or attacks.