Stunting of fish is caused in the wild when there are too many fish for the given area of habitate. Too much competition for food leads to famine. The fish are eating just enough to live and not enough to grow larger. If it happens over a long period of time the fish skeleton will still try to grow at risk of burning off all the essential fats and protiens in the body. They get bone desiese, and their immune systems become very week. Usually they can be described as having a shorter than normal body with a large head, as the brain and cranium continue to grow stealing nutrients from the rest of the body. If kept in these conditions usually the fish will eventually die from malnutrition, or other desieses. This can also result in home aqauriums from underfeeding the fish, feeding poor quality foods, or from a hunger strike by the fish. Why would the fish hunger strike you ask? If the biological filter is too small to support the bioload of the fish the water conditions will worsen over time, and your fish will fast because of stress due to high, ammonia, nitrate, nitrites, and unsafe ph levels. Usually the fish will eat very little or nothing at all and will emaciate. After the biological filter levels out your fish may already be stunted and retain it's current size, except that it's immune system will be permenantly damaged. Large catfish can hunger strike for months without permanent harm, smaller catfish may only have a few weeks at best. Really just depends on the metabolism of the fish versus it's caloric intake. I have also seen cases where people decided to keep fish that grew too large for their tanks, but had a good enough biological filter to sustain the fish anyway. I am in the process of adopting a jau that someone rescued from a 55 gal aquarium. This fish can get over 6', and wiegh in at over 250 lbs. Usually if a rtc is kept in a small aquarium it developes sores and broken fins over time. It can also develope the crooked and disfigured tail and back mentioned above. Tsn break their snouts as they need lots of swimming room, and are skittish fish by nature. Just my 2 cent, don't stunt, it's not a healthy alternative to keeping a fish in a proper sized environment.