An efficient mass culture method for Beroe cucumis

Abstract

This study reports an effective and simple method for culturing the comb jellyfish, Beroe cucumis. The method for breeding another comb jelly, Bolinopsis mikado, was published by Ikeda et al. (2022), in which Bolinop-sis mikado was bred stably and in large numbers, and then provided as food to developing Beroe cucumis. Fertilized eggs were found in a 235-L tank two days after five parental Beroe cucumis were housed in the tank, and the parental individuals were isolated from the tank the next day. The day after the eggs were found, Beroe cucumis larvae (0.54 ± 0.04 mm long (n = 9)) were observed in the tank daily and were fed Bolinopsis mikado. The Beroe cucumis larvae were only fed Bolinopsis mikado during the early stages of development. They reached a total length of approximately 10 mm in 17 days, and by day 20, when most had grown large (approximately 12 mm and over) enough to not pass through the 3-mm perforated plates, they were moved to a 145-L display tank. Thereafter, they were reared in the same manner and were successfully propagated cumulatively for more than five generations. The greatest advantage of this culture method is that the larvae need only be fed and observed until they reach the size required for display. Therefore, stable breeding of Beroe cucumis can be achieved by feeding its larvae with Bolinopsis mikado, reducing labor and stress on the organisms from frequent water changes.