O2 uptake through water during early life of Heteropneustes fossilis (Bloch)

Sheel, Manju; Singh, Bal Ram

doi:10.1007/bf00011944

Cited by 8 publications

(1 citation statement)

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“…The reproductive activity is temperature dependent, with 22°C being the reproductive temperature optimum. The eggs are tended by both parents who perform fanning movements with their fins to refresh the water around the eggs (Sheel andSingh 1981, Saxena andSandhu 1994). Egg incubation was found to take from 18 to 24 h, depending on the water temperature.…”

Section: Introductionmentioning

confidence: 99%

Embryogenesis of the Stinging Catfish, <I>Heteropneustes Fossilis</I> (Actinopterygii: Siluriformes: Heteropneustidae)

Korzelecka-Orkisz¹,

Smaruj²,

Pawlos³

et al. 2010

Acta Icth et Piscat

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Background. The stinging catfish, Heteropneustes fossilis (Bloch, 1794), has recently raised interest among fish farmers, ornamental fish keepers, and pathologists. Its natural populations are threatened due to habitat loss and high fishing pressure. A number of factors may influence the reproductive success of this. The aim of this study was to assess the effect of one of such factors-the water hardness-on the course of the embryogenesis, the structure of the egg shell, the general morphology, and the behaviour of the hatched larvae. Materials and Methods. The fertilised eggs were incubated at a constant temperature of 23 ± 0.2°C in water of different hardness: 0ºGH (soft), 9ºGH (moderately soft), 18ºGH (moderately hard). Egg membranes of activated eggs were viewed under a scanning electron microscope. Also egg membranes strength and egg deformations were determined 1.5 h after fertilisation. Images of eggs and newly hatched larvae, recorded with the observation sets described above, were measured and analysed. Results. The study showed the eggs were surrounded by thin, translucent,~5 µm thick membranes equipped with numerous outgrowths on the external surface and porous on the inner side. The following observations were made within 828 h°(degree-hour) at 23 ± 0.2°C: the highest volume of eggs (1.16 ± 0.092 mm 3 ) was typical for eggs incubated in soft water (0°GH), while the lowest egg volume (0.99 ± 0.113 mm 3 ) was recorded in eggs incubated in moderately soft water (9°GH); yolks spheres were greenish in colour, the embryonic disc and the embryo itself being reddish; the embryo performed diverse movements (quasi-peristaltic, cardiac muscle contractions); after few hours of hatching, the pigments developed resulting in colour appearance; club-like primordial barbels were formed 24 h after hatching; the larvae commenced feeding on day 3 post hatching. Conclusion. Water hardness influences embryonic and larval development and the effects may be diverse. Low water hardness is recommended for egg incubation. However, the situation changed when the egg membrane protection ceased to exist at hatching. Increasing water hardness a few hours prior to the expected hatching time prevents larval deformation.Keywords: stinging catfish, Heteropneustes fossilis, embryogenesis, eggs, embryonic motorics, embryonic morphometry, water hardnessIn addition to the species' value for fish farmers, the stinging catfish-due to some structural and physiological peculiarities-has become interesting also for the ornamental fish trade. Recently, the species has become a study object for pathologists focusing on transmittable zoonoses.The stinging catfish occurs naturally in tropical waters of south Asia, general in bodies of water abundant in vegetation, oxygen-depleted due to decomposition of the plant material, and heated by the sun throughout the water column (Munshi et al. 1976, Pandey 1978, Pethiyagoda 1991, Kahl et al. 1997, Jayaram 1999.In its native habitat, the stinging catfish attains 70 cm of total length. The sexual dimorphi...

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Section: Introductionmentioning

confidence: 99%