First Description of Reproductive Behavior and Alternative Reproductive Strategy in the Deep-sea Fish, Careproctus pellucidus.

The reproductive biology of deep-sea fishes is largely unknown because of the difficulty of behavioral observations in this environment. In this study, the reproductive behavior of the deep-sea snailfish, Careproctus pellucidus, which lives at depths > 200 m, was observed in an aquarium. To the best of our knowledge, this is the first report to observe and describe the reproductive behavior of deep-sea fish under free-living conditions. Fishes were collected at a depth of approximately 300 m (36°70′ N; 141°00′ E) on July and August 2018 and kept for observation until March 2019. We observed that almost all spawnings took place between one male and one female. Males defended a spawning substrate against other males and exhibited body-wiggling behavior for both courtship and aggressive display. Females visited the male’s territory and spawned a demersal adhesive egg mass on the substrate. The territorial male then sought the spawned eggs using filamentous rays in the lower pectoral-fin lobe and released sperm when he located the eggs. Males remained near the spawning substrate after spawning but did not perform any parental care. Notably, sneaking behavior by a non-territorial male was observed in one case; this is the first report of this alternative reproductive strategy (or tactic) in a deep-sea fish. Our study reveals the unique reproductive biology of the deep-sea fish, C. pellucidus, which does not depend on visual information and uses other sensory modalities.

Ecological groups of fish according to the substrate on which they spawn

The article deals with the reproduction of fish. Fish reproduce at different ages. Reproduction occurs at different times in the life of fish. Most fish reproduce by spawning. The spawning conditions of fish are very different. The eggs are fermented in water. Depending on the choice of spawning substrate, fish are divided into 5 ecological groups. Key words: Kura, ecology, caviar, Acipenseriformes, Clupeonella

Spawning habits and embryonic development of the lampeye killifish Aplocheilichthys spilauchen in ex situ fresh-and-brackish water environments

Aside from ornamental uses of killifishes, there is growing interest in using killies for a multiplicity of purposes including baitfish and mosquito biocontrol. This experiment explored the spawning habits and embryonic development of the banded lampeye, Aplocheilichthys spilauchen in ex situ freshwater (0.04 ‰) and brackish water (5.01 ‰) to ascertaining the captive breeding prospects for mosquito control in areas where they occur. Significantly higher number of eggs were laid in the brackish water than the freshwater (ꭓ2 = 1613.0, P < 0.05), and black mop was the most preferred spawning substrate, followed by green, blue and white mops. Microscopic monitoring of embryos revealed that cleavage occurred within the first 30 minutes after fertilisation, organogenesis commenced in averagely the 25th hour, and hatching in approximately 230 hours. Although certain embryonic developmental stages occurred faster in the freshwater than brackish water and freshwater eggs were relatively bigger than brackish water eggs, these differences were overall not significant and had no effects on the development and hatching. The observed outcome that A. spilauchen can be optimally propagated with black mops in brackish water offers a significant step in its use for the mosquito biocontrol programme, as well as other potential uses not yet explored.