FIRST REPORT OF Pterygoplichthys disjunctivus AN EXOTIC INVASIVE, SUCKERMOUTH CATFISH FROM ARANI RIVER, TIRUVALLUR DISTRICT, TAMIL NADU

Arani is a non-perennial West to East flowing river originating from the hill streams of Eastern Ghats, Andhra Pradesh and drains into the Bay of Bengal via the Pulicat Lake in Tamil Nadu. Total stretch of the river is about 108 km, of which about 43 Km flows through Chittoor district in Andhra Pradesh and 65 Km in Tiruvallur district, Tamil Nadu. The river possesses rich aquatic biodiversity and forms an important source of protein to the locals in that region. But the recent ichthyofaunal diversity study conducted in the River Arani revealed the occurrence of the exotic invasive Vermiculated sailfin suckermouth catfish Pterygoplichthys disjunctivus. The occurrence of the invasive suckermouth catfish and possible threat it possess on the native fish fauna is discussed here.

Two suckermouth catfish specimens were collected from Arani River, Tiruvallur District during a bi-monthly sampling. The specimens were photographed and fixed in 5% formalin for identification. Meristics and morphometry followed Ozdilek, S.Y., 2007. Local fishermen were contacted to gather information on its occurrence in the catches.

The collected suckermouth catfishes were identified to be Pterygoplicthys disjunctivus, a species native to South America. During the survey a total of 50 species of native fish fauna were documented including Pethiasharmai, an endemic and endangered barb of Chennai, Tamil Nadu.  The family Cyprinidae were dominant with 17 species. The occurrence of P. disjunctivus in the Arani River may possess a great risk to native ichthyofauna due to their predatory grazing nature, competition for food and space. Discussion with the native fishermen revealed that, its population in the river is increasing gradually in the recent times and frequently landed in the gill net catches.

Poor bio security in the ornamental fish farming and deliberate release of aquarium specimens in the native aquatic bodies are the root cause of all alien fish invasions. A proper awareness and implication of bio security rules and regulation must be implemented to prevent and control the invasion of alien fishes.