From experience and research, there are many factors that can cause slow growth in catfishes and tilapia and they are
 
1.  Bad Or Poor Water Quality
 
Optimum water quality guarantees a high growth rate of catfish. This is because dissolved oxygen is adequate, dissolved carbon dioxide is low, pH is normal, dissolved nutrients are present at required concentrations.
 
Poor water slows down the growth of catfish and tilapia. Take your water quality management serious.

 
2. Poor Quality Of Feeds And Underfeeding
 
Unbalanced, substandard, or adulterated feeds lead to poor growth of fishes or even death. It is necessary to buy your feeds from an accredited and reliable dealer to avoid stories that touch the heart. If you produce your own feeds, make use of high-quality ingredients from reliable supplier or dealer and make use of the right feed formula for the specific age of your fishes.
 
Higher quality feed and feeding the required amount of feeds results in a faster growth rate of fishes. 
3. Poor Quality Of Fish Seed
Poor quality fries, fingerlings, or juveniles stocked will not grow well. This may be due to the poor genetic ability of the fish or poor health condition of the fish seed.
 
Some fish species are genetically superior in growth rate than others. This could be because of a high feed conversion and disease resistance characteristics. The growth rate of fishes can be improved through breeding.
Some fishes also have a poor health condition or lack of resistance to some diseases. This could be because of the broodstock used to produce the fish seeds or a hatchery error. 
 
In all, avoid bad fish seeds when stocking your ponds to avoid high fish mortality or (and) poor growth.
 
You can read more on solutions to poor water quality, poor quality of feeds, and poor quality of fish seeds

 
 4. Overstocking Your Catfish Pond
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An overstocked or overpopulated fish pond is usually associated with a poor growth rate of fish. This is because of the high rate of competition for food, available oxygen, and space. In most cases, the bigger or more aggressive ones eat the weaker and smaller ones.
Make sure you stock the fishes at the optimum density required for adequate growth and development.
 
1-4 fishes per meter square for extensive system
4-10 fishes per meter square for semi-intensive system
10- over 100 per meter square for an intensive system.
 
Stocking capacity is dependent on management practice.
5. Sex Of The Fish
Most female fishes (both catfish and tilapia) convert most of their energy (consumed feed) to egg production and not flesh accumulation. Therefore, this makes them not to grow bigger compared to their male counterparts.
 
Stocking of only male fishes (catfish and tilapia) guarantee a higher growth rate and flesh accumulation.
 
6. Fishes not being in good health
 
Tilapia and catfish with a poor health condition are usually associated with poor growth rate. 
 
Poor health may be as a result of nutritional deficiency, poor water quality, overcrowding, and handling stress.
 
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