Growth parameters of Pseudetroplus maculatus (Family: Cichlidae) from three different ecosystems of central Kerala, India

Abstract

The orange chromide, Pseudetroplus maculatus (Bloch 1795), is an important food and ornamental fish endemic to the brackish water streams, lagoons, estuaries, and lower reaches of rivers in peninsular India and Sri Lanka. It is a monogamous, substrate-brooding cichlid characterized by distinct pair formation, mating, and parental care behaviours. The present study describes the length–weight relationships (LWRs) and relative condition factor (K) of this species collected from three different localities in central Kerala. A total of 1,099 individuals were collected and examined during the period 2018–2020. Sites I and II comprised channels adjoining paddy fields, whereas Site III represented an open-water habitat.  The estimated b values of the LWR were 2.934, 2.834, and 2.654 for Sites I, II, and III, respectively, and all values differed significantly (p < 0.05) from the theoretical isometric value of 3, indicating negative allometric growth. The condition factor (K) ranged from 1.23 to 2.81 (1.90 ± 0.195) at Site I, 1.19 to 5.28 (2.02 ± 0.348) at Site II, and 1.15 to 2.99 (2.03 ± 0.22) at Site III. The relatively high mean condition factor observed across all three sites indicates good body condition and overall well-being of the fish in these habitats. Site III exhibited the highest mean K but the lowest b value, highlighting that condition factor and the LWR coefficient represent different aspects of fish biology and may not necessarily show a direct relationship. The observed spatial variation in growth pattern and condition may reflect differences in food availability, habitat characteristics, environmental conditions, and population structure among the study sites. These findings provide useful baseline information on the growth characteristics and well-being of P. maculatus in different habitat types of central Kerala.