Effects of Cadmium Exposure on External Morphometric Traits of Trichopodus pectoralis (Snakeskin Gourami)

Heavy metal contamination, particularly cadmium, poses a critical threat to Malaysia’s aquatic ecosystems due to its toxicity, persistence in the environment and bioaccumulative potential. Such contamination threatens biodiversity sustainability and public health, as consumption of contaminated fish can elevate human health risks through biomagnification. Trichopodus pectoralis, a sensitive biological indicator, was selected to assess cadmium’s sublethal effects on external morphometric traits. Juvenile Trichopodus pectoralis were exposed to four cadmium concentrations (0.000 mg/L, 0.005 mg/L, 0.010 mg/L, and 0.015 mg/L) over 16 weeks, with morphometric analyses performed at four-week intervals using descriptive statistics and the Kruskal-Wallis’s test. The findings revealed that cadmium exposure significantly affected most external morphometric traits, including snout length, head length, postorbital length, pectoral fin length, body depth, caudal peduncle depth, standard length and total length (p < 0.05). Interestingly, traits such as postdorsal length increased at the highest concentration, suggesting compensatory responses. External morphometric traits of T. pectoralis serve as reliable indicators of cadmium toxicity. Notably, the current National Water Quality Standards threshold (0.010 mg/L) already impairs juvenile fish, highlighting the need for stricter monitoring and revision of safety margins to protect biodiversity and public health.