# Breeding and Ontogeny of the Aquarium-Traded Scissortail Rasbora (Rasbora trilineata)

## TL;DR

This study outlines a successful method for breeding and raising scissortail rasbora in captivity to reduce reliance on wild populations for the aquarium trade.

## Contribution

The study introduces effective hormone dosages and feeding protocols for breeding and rearing scissortail rasbora.

## Key findings

- Using 15 μg/kg and 7.5 μg/kg of Suprefact® for females and males, respectively, improved spawning and survival rates.
- Feeding Chlorella for 14 days and Moina until 40 days significantly enhanced larval survival.
- Developmental stages from fertilization to juvenile were documented, with hatching occurring within 18 hours at 28–30°C.

## Abstract

Small-sized fish with a maximum length of around 10 cm are native to Southeast Asia and are popular as ornamental fish. Due to the decline of the wild populations, this study investigated a method for artificial breeding, stimulated using the synthetic hormone Suprefact®, with dosages of 15 and 7.5 μg per kg for mature females and males, respectively. The green algae “Chlorella” was used as their feed for the first 14 days after hatching, followed by the small crustacean, “Moina”, until they were 40 days old, with a juvenile size of around 2 cm. Moreover, this study also documented the key developmental stages from fertilization to hatching as well as development from the larval to juvenile stages. These findings provide essential knowledge for developing breeding programs and reducing dependence on wild populations for the aquarium trade.

Breeding and ontogeny development of the scissortail rasbora (Rasbora trilineata) was studied for conservation and enhancement purposes. A wild broodstock was collected from a reservoir in Surin Province, Thailand. Breeding was done by injecting the synthetic hormone Suprefact® to induce spawning. The suitable dosages for mature females and males were 15 and 7.5 µg per kg of fish, respectively (p < 0.05), compared to other treatments measuring numbers of spawned eggs, fertilization rates, and survival rates at 24 h. Chlorella was used to nurse the larvae for 14 days after hatching (DAH). Moina was used to rear the larvae until they reached 40 days old since this provides significantly higher (p < 0.05) survival rates comparable to other artificial feeds in the experiment. For ontogeny, this study documented cleavage, blastula, gastrulation, segmentation, and the pharyngula period, which culminated in hatching within 18 h at 28–30 °C. The larvae exhibited rapid growth, reaching 2 cm in total length by 40 DAH, which is suitable for trading or stocking for resource enhancement.