Researchers at Kerala University of Fisheries and Ocean Studies in Kochi have examined the world’s smallest pufferfish’s habits in captivity and its embryonic development. They discovered that the puffer has unique reproductive behavior and character, contributing to its low fecundity.
The Malabar dwarf puffer Carinotetraodon Travancoricus is one of the smallest pufferfish, endemic to India’s Western Ghats Biodiversity Hotspot. The dwarf puffer is extensively exported due to its demand as ornamental fish. Estimates state that more than one million dwarf puffer fish are collected and exported.
However, unlike other puffers, the elaborative study of its embryogenesis, hatching, and larval rearing has not been documented yet. Studying such accounts is essential to understanding their genetic imprints and broader applications.
“Developing captive breeding techniques is the key to maintaining the sustainability of an aquaculture production system. Despite the huge demand for C. Travancoricus in the aquarium pet trade, research approaches on captive breeding and early development have been limited,” says the study.
To holistically study the behaviors of the Malabar dwarf puffer, researchers created a suitable environment, and adult fish were procured from an aquarium fish supplier. The team fed the brooders with bloodworms and moina twice daily, maintaining temperature and pH values.
Once the breeding tanks were ready, scientists carefully collected the eggs from the shallow water of the river. As the eggs were laid between pebbles, they were carefully collected and transferred to the tank.
Researchers observed the embryonic development of the fish, which shows distinct sexual dimorphism at the mature stage. The mature male had a prominent mid-ventral keel, central round wrinkles around the eyes, and a dorsally and ventrally curved body. Meanwhile, the mature female fish had a bulged belly and distinct black blotches on the body.
The Malabar swarf puffer demonstrated intense courtship behavior in the late evening, culminating in egg release. During the spawning, males were often observed guarding the area where females spawned eggs.
Strangely, the dwarf fish spawns only one to five eggs daily, adding to their low fecundity.
The eggs are non-sticky and spherical, found in pebbles. It takes four to five days for hatching.
Journal Reference
- Chandana B, Sanal A, Raghavan R, Varghese B. Embryonic development of the world’s smallest puffer fish, Carinotetraodon travancoricus – a threatened freshwater fish of the Western Ghats Biodiversity Hotspot. Zygote. Published online 2024:1-8. DOI: 10.1017/S0967199424000273