Marine Ornamental Fish & Invert Breeders Association

by **mpedersen** » Sat Mar 10, 2007 2:19 am

Dragonette / Mandarinfish - Callionymidae - Breeding, Mating, Spawning and Rearing Overview

1 - Species covered in this forum:
The Family Callionymidae - fish in this family are often incorrectly referred to as "Gobies" or "Blennies" but in reality are distinct - they are Dragonets or Dragonettes. This family includes popular species such as:
Dactylopus dactylopus - the "Fingered Dragonette"
Synchiropus splendidus - the "Mandarinfish", "Green Mandarin" or "Mandarin Goby"
Synchiropus ocellatus - the "Scooter Blenny"
Synchiropus stellatus - the "Red Scooter Blenny"
Synchiropus picturatus - the "Psychodelic Mandarin", "Spotted Mandarin", "Green Mandarin"

For an overview of the Callionymids, see http://www.fishbase.org/identification/ ... s=&c_code=

2 –Common characteristics:
Dragonettes are often considered to be difficult fish to keep in captivity...they can be difficult to get onto foods and are slow deliberate feeders, primarily consuming copepods, amphipods and other small organisms. It is often suggested that fish from this family require a minimum of 50-75 gallons of tankspace per fish, and only in a well established "reef aquarium" (set up at least 6 months or longer) where ample supplies of small invertebrate life are able to sustain these constant pickers.

Several aquarists have found success with training Synchiropus sp. onto frozen and prepared foods, borrowing from methods often employed in the rearing of Seahorses. For the individual interested in propagating Dragonets, it is crucial to select healthy candidate broodstock from the get go...trying to "rescue" specimens that are already starving can prove difficult if not impossible. It is likely that training onto frozen or prepared foods is most likely the critical step towards proper conditioning (and frequent spawnings).

For more basic information, visit - http://www.wetwebmedia.com/mandarins.htm

3 – Reproduction:

3.1 – Sex determination:
Separate sexes - there is no evidence of any hermaphrodism in the Dragonets.

3.2 – Sexual organization:
Pairs; Harems (multi-females); Groups. True "Pair Bonding" does not seem to occur - Females are said to prefer larger males. Aquarium observations suggest that a male may attempt to mate with more than one female in the course of an evening. In small aquariums, maintenance of a 1 male / 1 female pair seems to work best - individual fish seem to be intolerant of other members of the same sex.

3.3 – Sexing:
Sexual dimorphism; many species show different structuring of the first dorsal fin, which is generally more elongate or elaborate in males.
Sexual dichromatism; some species show different coloration, typically again in the first dorsal fin (i.e. Male S. stellatus have an orange dorsal fin with various scribbles and ocelli; Females typically have a dark or black dorsal fin edged in white). Sexual distinctions may be present in small specimens (i.e. in a recently observed group of approximately 1 dozen tiny wild caught S. stellatus, individuals at 1" (2.5 cm) already showed both dichromatic and dimorphic traits).

3.4 - Pairing / Setting Up Broodstock:
In small aquariums (i.e. 20 gallons), it is often as simple as chosing one male and one female and placing them in the tank together. There may be some initial occasional skirmishes, but the quarrelling is seldom life-threatening and typically subsides in a couple weeks.

Again, it seems that in tight quarters, having multiple individuals of the same species AND same sex does not work - larger females will attack smaller females and the same can be said for males. However, keeping pairs of different species (i.e. 1m/1f S. splendidus with 1m/1f S. stellatus) seems to work out just fine, as the species seem to simply ignore each other.

It is suspected that in larger aquariums (i.e. 200 gallons) that something like a spawning group consisting of 2 males and 4 or more females per species may work long term, and would present a situation more similar to the natural "pairing scheme" for the species in question.

It is also worth mentioning that while some species have spawned in aquariums as small as 10 gallons, due to the nature of courtship and spawning a tank with considerable height is desireable for breeding purposes.

3.5 – Courtship:
In the wild, observations of species such as S. splendidus suggest that females gather in small open patches towards sunset, and males gather and display, attempting to catch the interest of a female. Once a female selects a mate, the pair rises into the water column, spawning at the end of their ascent.

In the aquarium, observations of several Synchiropus sp. show a pretty defined courtship process. Courtship starts as early as 1 hour before "lights out" with the male displaying to the female. To display, the male positions himself in perpendicular to the female and in front of her, flaring all fins and sometimes shimmying. As the evening progresses, if the female is agreeable to this point, the male will come alongside her, again flairing his fins. If the female accepts his advances, the pair will rise, side-by-side in the water column - this is the "Dance". At the apex of their spawning rise, the pair will part and descend, the male then relocating the female, again displaying, and again rising. In tanks with adequate vertical room, the pair will end their rise below the surface. In shorter tanks, the pair may come to the surface and continue the paired swimming along the surface of the tank.

The "dance" may occur before lights out, and often continues after the main aquarium lights have turned off. Many aquarists who maintain pairs of dragonettes may have no idea that their fish are even attempting to spawn as this all occurs in the evening, and most often spawning only occurs after lights out. This is one of those situations where "moonlighting" combined with nightly observations will help you notice if your fish are attempting to spawn.

The repetition of this dance may occur many times or just a few. The female may chose to break off courtship during this phase, retiring to her typical sleeping location. When this happens, the male will actively search the tank for other willing participants. When the female decides to continue with the dancing after many attempts, typically this is indiciative that spawning will occur.

For lack of a better term, "false spawnings" may occur, where all the behaviors of an actual spawn happen as described below, but no eggs or sperm are released. Could this be to simply help the pair "synchronize" their bodies to each other before the actual spawn? See below.

3.6 – Spawning:

Spawning always occurs after the main aquarium lights have turned off - typically anywhere from 5 minutes to an hour later. Spawning occurs at the end of a dancing / rise, with the male and female rapidly churning their fins, their genital openings in close proximity. The release of eggs and sperm at the water's surface is extremely rapid, lasting only a second or two. Once this has completed, the pair quickly break apart and dash back to the tank floor. Once spawning has occured, the pair go their separate ways. Typically, the female will retire to her sleeping location in short order..the male may briefly check the tank as if looking for other willing females.

4 – Eggs:

4.1 – Size:
Eggs are small, around 1mm from both S. splendidus & S. stellatus

4.2 – Quantity:
Spawns as large as 600+ eggs have been counted in captive S. splendidus.

4.3 – Characteristics
The eggs float at the water's surface. There is no discernable oil globule present in the eggs (i.e. compared to the highly visible oil globule found in Centropyge sp. eggs)

4.4 – Incubation period/Hatching temp:
The eggs of Synchiropus sp. seem to take 12-16 hours to hatch at temperatures of 28C (82F).

5 – Larvae:

5.1 – Size at hatching: approx 2mm
5.2 – Yolk sac present at hatch: Yes
5.3 – Mouth present at hatch: No
5.4 – Eyes developed at hatch: No

6 - Rearing:

6.1 - Breeding & Rearing Techniques
Always turn off circulation and filtration pumps when Dragonettes are courting - this prevents loss of the eggs to surface skimming devices. Most all breeders agree that the eggs are rather delicate and can easily be damaged by heavy currents & aggitation.

Following spawning, eggs can be removed either by scooping them from the water's surface or with a pipette (provided the opening of the pipette is large enough to allow several eggs to enter at the same time).

Several different descriptions of egg incubation methods have been proposed by various breeders, and no one technique is the "clear winner". Techniques range from simply setting the eggs in a specimen container within a larger aquarium (to maintain heat in the small specimen cup) with no aeration, to fish-bowl kriesels and stirring mechanisms that gently stir the water. Water for egg incubation could be sterilized or can even been water from the broodstock aquarium. Once hatched, the larvae are then separated or released.

6.2 – Day at first feeding:
2-4 days post SPAWN.

6.3 - Starvation Time:
If known, include the time post-hatch that larval will live without feeding. This can often be found in larval studies where scientists do not feed the larvae, as well a accounts of failed larval rearing attempts.

6.4 – Feeding scheme:
Following hatch, the best bet for attempting to rear these larvae is utilizing greenwater techniques including phytoplankton such as Nannochloropsus, Nannochloris, Tetraselmis or Isocrysis (T-Iso). Zooplanktons could include SS-Strain Rotifers and Copepod nauplii - copepod nauplii seem to be one of the better performing routes to take - these nauplii must be free swimming, so most folks are focusing on the Calanoid copepod species.

6.5 – Age at meta:
Synchiropus sp. do not have a clearly defined metamorphosis period...rather it seems to be a gradual transition. Settlement to the bottom may start occuring around 14 days, with juveniles looking like miniature adults at 8-10 weeks.

7 – Species been reared successfully
Synchiropus splendidus - perhaps first reared by Julian Sprung in the early 1990's. Since then, reared by Wolfgang Mai, Dr. Sadovy, RCS, Sylvio, Wittenrich, Lautan (French Aquaculture company) and probably others.
Synchiropus picturatus - as far as we know, only reared by Mai and M. Reith, most recently by Lautan (French Aquaculture Company)
Synchiropus ocellatus - there is an unconfirmed report of a hobbyist having reared this species successfully (see http://www.marinebreeder.org/phpbb/viewtopic.php?t=4447 )
Synchiropus sp. - Frank Baensh has reared an unidentifed sp.

by **mpedersen** » Sun Apr 06, 2008 11:33 pm

Marine Ornamental Fish & Invert Breeders Association

Dragonettes & Mandarinfish Breeding/Spawning Overview

Dragonettes & Mandarinfish Breeding/Spawning Overview

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