A succulent dish made of ‘Green Chromide’, also known as ‘Pearlspot’ or ‘Karimeen’ locally, is considered emblematic of the famed fish preparations of Kerala. It has also been declared as the ‘official fish’ of Kerala.
However, according to a recent study conducted by the Kerala State of Fisheries and Ocean Sciences (KUFOS), several indigenous fish species in the state, including the ‘Pearlspot’, are facing serious threats from exotic fish varieties.
A research team, comprising B Madhusoodana Kurup, vice-chancellor, KUFOS, and M P Prabhakaran and Ratheesh Kumar, both assistant professors of the same University, has revealed that the ‘Three Spot Gourami’, an exotic fish species belonging to the Osphronemidae family, is proliferating in the freshwater ponds and canals of Pollathai, a village near Kalavoor, Alappuzha, raising concerns about its impact on the indigenous fish species of Kerala.
The study says that the invasion of the species has resulted in the depletion of indigenous fish species such as ‘Pearlspot’, and other locally popular species such as ‘Orange Chromide’ (Pallathi) and ‘Malabar Danio’ (Paral), among others. The KUFOS team has also found that the presence of this invasive species has resulted in the habitat destruction of indigenous fish.
The ‘Three Spot Gourami’, introduced in India as ornamental species exclusively for aquariums, belong to the fresh water wetlands of Africa and South Asia. Gouramis are predominantly algal feeders but could turn omnivorous or carnivorous. It is territorial, aggressive and a resource competitor and these pose threats to the indigenous fish populations.
According to Kurup, the prolific breeding capacity of the ‘Three Spot Gourami’, together with its high fecundity, makes it an invasive species which affects the habitats of the indigenous fish species. “The invasion of exotic breeds is one of the major biodiversity threats to the 270 inland fish species in Kerala. The Periyar lake, which harbours more than a dozen endemic fishes, and many other species new to science, has now been invaded by the ‘African Muzhi’, Common Carp and Tilapia. The introduction of ‘Tilapia’ to the Vembanad Lake has resulted in the reduction of ‘Pearlspot’, owing to competition for food and space”, said Kurup