Breeding of Halichoeres melanurus - Melanurus wrasse

Over the course of 4 years, various reports on the offspring of the Melanurus wrasse were published on the homepage of Risingtide . Below is a short summary.

In February 2015, six adult Melanurus wrasses (3 male and 3 female) were brought to the Tropical Aquaculture Lab. Once the wrasses got accustomed to their new environment and fed LRS Reef Frenzy, PE-Mysis shrimp and Otohime EP1 pellets, they spawned every night.

This species is a protogynous hermaphrodite, meaning fish transition from females to males as they mature based on social structure. Females can be identified by the presence of the third black spot at the front of the dorsal fin. The first step these fish make in transitioning from female to male is the loss of that particular spot, so this acts as a great way to identify females. Females can get along fine in groups, however males will compete for territory and only the largest terminal phase male will survive. Spawning these fish in small harems of one terminal phase male with three to four females seemed to worked well.

One to two hours before the tank lights turned off the male would rise to the highest point of structure in the tank and begin a vibrant display for the females followed by continuous chasing. The male would then find an accepting female and the pair would spawn hundreds up to several thousand pelagic eggs into the water column.

Melanurus wrasses at dusk. Note in slow motion that all three males try to fertilize the female eggs.

The eggs were about 660µm in diameter. Despite this small size, larvae hatch out relatively large (~2.5mm) but with a very small mouth gape (~125µm).

Larvae were reared in a static 5 gallon aquarium and were ready to feed at 3dph (days post hatch). At that point, the rearing water was darkened with T-ISO and larvae were fed Parvocalanus crassirostris nauplii at 1-2 nauplii/mL.

Melanurus larva 15 days dph eats Otohime-A

Lights were on continuously until larvae were 12dph and over the next 8 days lights were transitioned down to a 14 hour light: 10 hour dark schedule. Varying size fractions of copepod nauplii were maintained in the tank throughout the rearing process and at 14dph Otohime A micro diet (75-250µm size) began being fed to larvae. Larvae reached flexion by 15dph and were settled juveniles by 22dph.

Melanurus wrasse juvenile, 36dph.

Melanurus wrasse, Halichoeres melanurus, 44 days after hatching

Update 2016:

The University of Florida's Tropical Aquaculture Laboratory (TAL) is currently working with two types of wrasses. Melanurus wrasse ( Halichoeres melanurus ) and yellow wrasse ( H. chrysus ). Three different breeding populations of the Melanurus wrasse are kept in different sex ratios and are fed four to five times a day with a varied diet in order to promote spawning behavior and to ensure the production of high-quality eggs. Uniform daily spawning of two of the Melanurus wrasse populations gives 100 to over 2,000 fertile eggs with an average diameter of 0.604 mm. Preliminary larval rearing experiments, which investigated the effects of different environmental conditions in large (125 l) and small (13 l) culture tanks, have recently led to successful larval rearing. During this trial, nine healthy, postmetamorphic pups were reared, representing a 1% egg-to-hatch survival.

These juveniles are now over two months old (the wrasses shown in the video are from this experiment and the video was taken two weeks after the conversion). The first larvae from this experiment settled and completed the metamorphosis 37 days after hatching. While this trial appeared somewhat delayed compared to our earlier efforts, this is the largest group of melanurus wrasses that have been bred at the TAL so far. Efforts to replicate and improve on this success are underway and include studies on optimal incubation and larval rearing temperatures, stocking densities, light intensities, live feed densities and other culture parameters.

Update 2019:

The team at the UF/IFAS Tropical Aquaculture Lab recently settled ~60 Melanurus wrasse, Halichoeres melanurus, the largest cohort of wrasses ever brought through to settlement at the lab! This success was achieved in the newly renovated larval room that was updated with improved systems and lighting. The team reports that with this cohort they modified the larval feeding protocol; starting rotifers on day 10 and microdiets on day 21. They observed the first settled larvae on day 36, and the larvae are currently 46dph.

The advancement brings us one step closer to commercializing culture for this species.

Update 06.12.2019

The juvenile fish are now 62 days old. The count showed 78 juvenile fish. Next you will be relocated to larger basins and divided into smaller groups. This can cause a lot of stress for the young fish as they switch to a system with changing light conditions. With a size of 2'' we will coordinate with Rising Tide Conservation partner aquariums to have them displayed in their exhibits.

This success was the result of the hard work of Rising Tide Conservation graduate student Grace Sowaske, PhD candidate Casey Murray, Sarah Hutchins, and the rest of the Rising Tide team at the UF/IFAS Tropical Aquaculture Lab.

The lab thanks Quality Marine for their help in acquiring the broodstock, and Rising Tide Conservation and the SeaWorld Busch Gardens Conservation fund for their continued support.

Update 21.02.2020

The Melanurus wrasse cohort is currently 139 dph and we settled collectively 78 individual wrasses from that single batch of eggs. Here are a few pictures of one from today (this one measured approximately 3.5cm/1.44in total length (TL)).