A common misconception new aquarium owners have is the number of bottom feeders and tank maintenance fish that you need. The most common all in one algae eater, bottom feeder, and waste cleanup fish that you can buy at the pet store is called a Plecostomus, more commonly known as a Pleco or “suckerfish”. Plecos eat algae off the side of the aquarium, they eat excess food off of the substrate, and they help keep your aquarium clean 24/7. The problem that people have is they don’t understand that you only need one.
If you have an algae problem and don’t have any type of algae-eating fish, you need a pleco. Within about a week, your tank will be looking much nicer and your fish will have a good meal every day. If your tank is brand new and sparkling clean, I don’t even recommend getting a pleco for about a month, and when you do get one, find the smallest one at the pet store. Plecos eat algae and excess food, so if your tank is brand new, you probably don’t have a lot of algae or substrate waste for them to eat. Buying the smallest pleco in the store requires less food, so they have a higher chance of being successful in your clean tank.
If you decide to buy two plecos, they will both be trying to survive on the same food source. Chances are, one pleco would be more dominant and the other one would die. You only need to purchase one pleco for your aquarium to keep things clean. If you feel that the pleco alone isn’t doing a good job, you can always buy a single catfish or another bottom feeder. If you buy a small pleco, they will require a small amount of food at the beginning, but you have to remember that these fish grow large and they grow fast. Your pleco will soon grow larger and require more food, thus cleaning your tank a little better.
Also, just remember that just because you have algae-eating fish doesn’t mean you don’t need to clean your fish tank. You should still do regular water changes, bi-monthly gravel vacuuming, and your normal cleaning cycle. Fish like the plecos are only to help with excess food and algae and don’t replace you physically cleaning the tank yourself.