Scavenger fish: myths and reality
The concept of cleaner fish is a dangerous myth. No fish keeps an aquarium clean on its own. They have their own needs.
Detailed explanation
The pleco sold as a cleaner grows to 30-40 cm and produces more dirt than it removes. Fish that eat algae or debris REDUCE the problem but do not eliminate it.
However, water changes, filter cleaning and bottom siphoning are necessary. Each fish has its own space and feeding needs.