NON-TUBERCULOSIS MYCOBACTERIUM INFECTION IN CLIMBING PERCH Anabas testudineus FROM THE WILD – A POSSIBLE THREAT TO FISH FARMING

Mycobacteriosis is a serious and often lethal disease of fish, affecting a wide range of species in wild and captivity. Non-Tuberculosis Mycobacterium (NTM) are aerobic, acid-fast,                Gram-positive, non-spore forming and non-motile bacteria that live in soil and water. Mycobacterial disease is an emerging disease that poses a serious threat to the fish farming industry and to the fish handlers as it is zoonotic in nature. Mycobacterial infection has been recorded in this study in Anabas testudineus collected from the wild. There is a likely possibility of transmission of this disease to other fish species sharing such common habitats and also to the farmed fishes in case of poor biosecurity in farms.

Anabas testudineus, climbing perch belongs to the family Anabantidae and are native to southern and eastern Asia. About 42 samples of A. testudineus were randomly collected from small pools and village tanks in Ponneri taluk, Tiruvallur district, Tamil Nadu (Figure1). Live Fishes were anaesthetized with a high dose of clove oil and the tissue samples were inoculated in Middlebrook 7H9 broth, incubated at 37°C for 7 days. Tissue samples were also subjected to PCR for confirmation by the amplification of hsp65 gene of Mycobacterium sp.

After 7 days of incubation, the growth of Mycobacterium sp was observed as typical pink colonies in twelve fish samples of                               A. testudineus (Figure 2). PCR amplification of hsp65 gene from the infected fishes resulted in the amplicons of ~644 bp fragment (Figure 3). Sequencing and comparison using NCBI BLAST showed that the isolate was Mycobacterium fortuitum with a nucleotide homology of 99% with the sequences in the NCBI records. The results of this study showed that wild fishes like                   A.testudineus would act as carriers of virulent Mycobacterium sp. and transmit diseases to the farmed ornamental and food fishes. Mycobacterium infection in fish also poses health risk to human beings due to its zoonotic potential. Hence, it is essential to prevent the spread of Mycobacterium infection by adopting proper biosecurity measures to prevent the transmission of the disease from the wild to farmed ornamental and food fish.

Hence, it is essential to prevent the spread of Mycobacterium infection by adopting proper biosecurity measures to prevent the transmission of the disease from the wild to farmed ornamental and food fish.