<b>Early ontogeny of <i>Clarias gariepinus</i> (Siluriformes, Clariidae) and aspects of its invasion potential in natural freshwater environments</b> - doi: 10.4025/actascibiolsci.v35i3.12471

Abstract

ABSTRACT. This study aimed to describe the early development of Clarias gariepinus, a species that has been introduced into various watersheds worldwide, in order to help the identification of its eggs, larvae and juveniles in natural environments. The material used was obtained via induced spawning during 1999. After spawning, the periodicity of sampling varied according to ontogenic development. We analyzed 12 eggs, 146 larvae and 6 juveniles. Newly fertilized eggs are spherical, with a double membrane, the density of which varies. Initially the larvae have little pigmentation but this intensifies during development. They have four pairs of well-developed barbels, an elongated body, long dorsal and anal fins, no adipose fin and vesicles surrounding the finfold and barbels. The sequence of formation of the fins is: caudal, dorsal, anal, pectoral and pelvic. Growth pattern analysis revealed that metamorphosis usually occurs during the flexion stage. The reproductive performance of the species and its rapid early development favor aquaculture; however, they may also favor its invasion of natural environments, representing a threat for native populations.Keywords: african catfish, invasive species, larvae, juvenile of fish.Ontogenia inicial de Clarias gariepinus (Siluriformes, Clariidae) e aspectos de seu potencial de invasão em ambientes de água doce natural RESUMO. Este trabalho teve como objetivo descrever o desenvolvimento inicial de Clarias gariepinus, uma espécie introduzida em várias bacias hidrográficas do mundo, a fim de auxiliar na identificação de seus ovos, larvas e juvenis em ambientes naturais. O material utilizado foi obtido por meio de desova induzida durante o ano de 1999. Após a desova, a periodicidade na obtenção das amostras variou de acordo com o desenvolvimento ontogênico. Foram analisados 12 ovos e 146 larvas e 6 juvenis. Os ovos recém-fecundados apresentam forma esférica, com membrana dupla, sendo que sua densidade difere ao longo da membrana. As larvas possuem inicialmente pigmentação escassa, que se intensifica ao longo do desenvolvimento; quatro pares de barbilhões bem desenvolvidos; corpo alongado; nadadeiras dorsal e anal longas; ausência de nadadeira adiposa e presença de vesículas circundando a membrana embrionária e os barbilhões. A sequência de formação das nadadeiras é: caudal, dorsal, anal, peitoral e pélvica. A análise do padrão de crescimento revelou que a maior parte da metamorfose ocorre no estágio de flexão. O desempenho reprodutivo da espécie e seu rápido desenvolvimento inicial se enquadram positivamente à aquicultura, porém, podem ser altamente favoráveis à invasão de ambientes naturais, representando um risco para as populações nativas.Palavras-chave: bagre africano, espécie invasora, larvas, juvenis de peixes.

EMBRYONIC AND LARVAL DEVELOPMENT OF A RED STRAIN OF THE EGYPTIAN AFRICAN CATFISH (Clarias gariepinus Burchell, 1822)

“…Morphological development of the red and black strains larvae of Egyptian African catfish at the water temperature of 27°C-31°C was photographed as presented in Figure 4 and 5. In general, larval development of the red strain of Egyptian African catfish was similar to that of the black strain, as well as of other African catfish strains (Legendre & Teugels, 1991;Matsumoto et al, 2001;Sule et al, 2001;Mukai et al, 2008;Osman et al, 2008;Kipper et al, 2013;Olaniyi & Omitogun, 2013). However, there were slightly differences in the timing related to the chronological development of those reported C. gariepinus larvae.…”

“…Embryo movements and heart beating commenced respectively 840 and 860 minutes after fertilization, then more frequent prior to hatching. Embryo size increased, thus almost filled the whole egg space strains reported in the other studies (Legendre & Teugels, 1991;Sule et al, 2001;Mukai et al, 2008;Osman et al, 2008;Kipper et al, 2013;Olaniyi & Omitogun, 2013). However, periods of the embryonic development of those C. gariepinus strains were slightly different.…”

“…The present study was conducted to elucidate embryonic and larval developments of the red strain of Egyptian African catfish compared to those of the black one. While embryonic and larval development of the normal coloured C. gariepinus have already been reported by several workers (Legendre & Teugels, 1991;Matsumoto et al, 2001;Sule et al, 2001;Mukai et al, 2008;Osman et al, 2008;Kipper et al, 2013;Olaniyi & Omitogun, 2013), there was no report for those of the red coloured C. gariepinus.…”

“…Hatching of C. gariepinus in the Netherlands at water temperature of 24°C occurred at 40 hours after fertilization (Osman et al, 2008). In Brazil, the hatching occurred after approximately 30 hours of incubation at water temperature of 25°C (Kipper et al, 2013). Those differences were influenced by the water temperature, the higher the water temperature, the earlier the hatching taken place, as reported by Hogendoorn & Vismans (1980), Kamler et al (1994), Haylor & Mollah (1995) and Oyelese (2006), and as reported by Legendre & Teugels (1991) in H. longifilis and Dhara & Saha (2013) for C. batrachus.…”

“…The newly hatched larvae of other C. gariepinus strains were relatively bigger than both strains of the Egyptian African catfish. Total length of the newly hatched larvae of C. gariepinus in Malawi was 0.47± 0.11 cm (Matsumoto et al, 2001), in the Netherlands ranged 3.6-5.3 mm (Verreth, 1994), in Malaysia averaged 4.2±0.2 mm (Mukai et al, 2008), in Brazil ranged 4.1-5.3 mm (Kipper et al, 2013) and in Nigeria averaged 5.0±0.5 mm (Olaniyi & Omitogun, 2013). Again, those might be due to the differences of the strain, size, and age of the brooders.…”