Hello, Jason here with some lesser known facts about a very commonly purchased fish. Also known as the Common Pleco, the Trinidad Pleco, Hypostomus plecostomus, may be one of the most frequently offered algae-eating “sucker fish” in the aquarium market. It is sought after by many freshwater aquarists to solve their algae problems. But, the fact that is that though these fish can be effective algae eaters in a tank, they grow too large for most home aqauriums. A full grown Trinidad can grow to a length of 24 inches. That is about the same length as a 20 gallon tank. They have a pretty rapid growth rate, so it does not take them long to outgrow most tanks. Realistically, they should have a tank that is a minimum of 150 gallons, and even a tank of that size may not give these fish enough room to turn and move about freely.
As far as their diet goes, Trinidads are omnivorous. When they are small they will mostly feed on algae, but as they grow they have been known to feed on the slime coat of their tank mates. This can open other fish up to infection if left unchecked, and it can present a stressful environment as the tankmates are pursued by the pleco. Though they are not predatory fish, they have also been suspected of eating smaller tankmates from time to time, should the opportunity present itself. It is rare they turn down an easy meal, and if left with the right target, such a as weakened, ill, or slow-moving tankmate, they do have the ability to ingest flesh.
I would recommend this species of pleco for customers with large tanks and other larger fish that can manage unwanted advances from the pleco if it should get any ideas. These plecos can handle being housed with larger more aggressive fish because they have tough skin. They are usually left alone to graze on wood and rock or scavenge for leftover food in the substrate.
So what kind of fish do get if you want a sucker for your smaller tank? Consider a Clown Plecostomus (Panaque maccus), Rubbernose Plecostomus (Chaetostoma sp.) These stay much smaller, are non-aggressive and reasonably priced. There are many much more colorful plecos, too. Many of these more colorful species do not grow more than about six inches at the most, but they can be considerably more expensive. Leopard Frog Plecos (Peckoltia sp.) and Yellow King Tiger Plecos (Hypancistrus sp.) are two alternatives.
Another important thing to remember about plecos is they may not solve an algae problem occuring in your tank. Although they may eat some of the algae, it is unlikely they will be able to remedy an aggressive algae bloom, and they may not eat some types of algae. Some species do not eat algae at all. Remember to check all the possible causes of an algae outbreak including water chemistry and the lighting on the tank. Nitrates, phosphates and other problems can leave you with a fish you don’t really want and a blanket of green in the tank too. Plecos are interesting and can be very attractive additions to aquariums of any size. Let their unique qualities, and not their reputation as cleaners, be your motivation in adding them to your aquarium.