Catfish is the most widely produced fish in Indonesia. Catfish is able to fulfill the consumption fish in Indonesia that proved by many stalls are provide the various types of processed catfish. Abundant catfish production gives problems to the catfish farmers that they often forget the diseases suffered by catfish without knowing that it was affect to the production. The purpose of this research able to help catfish farmers in diagnosing catfish disease by providing information about the symptoms, causes, ways of prevention and treatment of catfish diseases that are implemented on android. This system applies forward chaining method in diagnosing catfish disease. The system was created using Android Studio 3.0.0 software by applying java programming language. The result of the system is an expert system of catfish disease diagnosis based on android. Testing data validation on the system provides high validity based on matching the diagnosis results with an expert. Features provided on this system work in accordance with the expectation of researcher based on black box testing. This system is able to be well received by user based on the user acceptance test with average percentage 83.6%.