The Chocolate pleco (Hypostomus plecostomus), also known as the sucker fish, is a staple of the aquarium hobby, and is easily one of the most popular fish available. They are found throughout South America, and have in recent years been reported as an invasive species in several countries, most notably in the several southern United States.
Their natural habitat consists of streams and rivers and they are also found in shallow, low oxygen ponds during the dry season. They tend to prefer slow moving water with sunken driftwood and plants that provide shelter during day. The reason that they shelter for much of the day is that they are nocturnal and are rarely active during daylight hours – a behavior that you can expect in the home aquarium. While many will become more active during the day after being kept in captivity for several months, they should always be provided with adequate hiding places such as caves, rock over-hangs or large pieces of driftwood.
Many of the plecos for sale in pet stores are juveniles, and don’t be fooled into thinking that they are a small fish. While most are sold in the neighborhood of only one to two inches, they quickly grow to aquarium busting sizes. It’s not unusual for a pleco kept in proper conditions to reach over 24 inches (60cm) in length – a size that will overwhelm most aquariums.
If you are looking to pick up a male and female pleco for breeding purposes, then you are about to be disappointed. They are incredibly difficult to sex, and while many people claim to have a system that can easily sex them based on their size, or the shape of their fins, it’s nearly impossible for the average person to determine their sex.
 
Species – Hypostomus plecostomus
Common Name – Chocolate Pleco
Origin – Rio Araguaya, affluent of Tocantins, Amazon system, Arunana, Goias, Brazil
Diet – Omnivorous
PH Range – Alkaline 6.5 – 7.5
Temperature – Tropical 24-29°c
Breed Type – egg layer
Max Size – approximately 60cm
Sex – Un-sexed