Introduced fish species and their characters in Lake Maninjau, West Sumatra

Abstract

The diversity of indigenous fish species in Lake Maninjau has been declining with the rise of local people’s activities. One of the causes is the invasive species, which are initiated by introduced species. This study aims to discover the species, distribution, growth pattern, and condition factor including information of the environmental condition, supporting the existence and growth of introduced fish species in Lake Maninjau. Sampling was conducted at four locations in Lake Maninjau; Bayur, Linggai, Sigiran, and Galapung. Fishes were collected by experimental gillnet which vary in mesh size, 0.5; 0.75; 1; 1.5; 2; 3; and 4 inches. These nets were set about 12 hours from 8 pm to 8 am on the next day, once a month in May, July, August, September, and October 2017. Four introduced fish species were observed and examined; there were Cichlasoma trimaculatum (Three-spotted cichlid), Oreochromis niloticus (Tilapia), Pterygoplichtys pardalis (Armored Catfish), and Oxyeleotris marmorata (Marble Goby). O. marmorata and O. niloticus were recorded at all of the sampling locations. C. trimaculatum was recorded in Galapung and Sigiran, while P. pardalis only found in Bayur. These dominant fish species have growth patterns each; there are negative allometric (O. marmorata), isometric (C. trimaculatum), and positive allometric (O. niloticus). Moreover, these three fish species have an almost 1.00 condition factor; there were 0.988, 1.024, and 1.001, respectively. Results and discussion infer that introduced fish species in Lake Maninjau were distributed at several locations with good growth and condition.