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The diet of adult specimens of black scorpionfish Scorpaena porcus (Linnaeus, 1758) and small red scorpionfish Scorpaena notata (Rafinesque, 1810), collected from the Algerian coast was studied using different coefficients and trophic indexes. The inventory of ingested prey indicates that the focal species have a diverse diet that covers different zoological groups. Their feeding spectrum is mainly composed of brachyuran crabs and other crustaceans such as isopods and shrimp. Fish and molluscs are only occasionally ingested. The vacuity coefficient average exceeded the estimated rate of 40%. The observed monthly fluctuations revealed a seasonal alimentary rhythm. The foraging activity of the two scorpionfish decreases in summer, during gonad maturation. This decrease is highlighted by the increase in the vacuity coefficient and the decrease in the repletion index. Despite a similarity in the food bolus, the two co-occurring fish exhibit a specialized diet. This was observed especially in mature individuals. In conclusion, our results demonstrated a very strong overlap of niches between two scorpionfish species.

This study provides elements on indices and the cycle of reproduction of the species Scorpaena porcus. The size of sampled specimens varied between 10.3 and 39.5 cm, with weight ranging between 25.1 and 656.7 g. The sex-ratio determined based on a sample of 343 individuals, was in favour of females (59.42%). The size at the beginning of the maturity was around 17.8 cm for females and 18.8 cm for males. The monthly evolution of the sexual maturity indicated that the spawning period occurs in summer, confirmed by the evolution of both the gonado-somatic index (GSI) and hepato- somatic index (HSI), as well as the oviparous reproduction mode of the species. The histological structure of the testicles was generally semi cystic. While the ovaries are characterized by the presence of stroma in the central cavity during the prematurity and gelatinous matrix at the maturity; the evolution of vitellogenesis started from the central cavity toward the peripheral cavity, surrounded by a thin membrane. The absolute fecundity of this species varied between 22600 and 93400 eggs, depending on the size, total weight and ovaries weight, whilst its relative fecundity varied from 97 to 258 eggs per gram of body mass for specimens weighting from 87.7 to 456 g. Females ranging from 18 to 24 cm in size, had a significant contribution in the reproduction of this species.