It seems only fitting that our first creature feature focuses on one of the first marine ornamentals to have been raised successfully in captivity, the Neon Goby, Elacatinus oceanops, (formerly Gobiosoma oceanops). First reared in the 1970’s the neon goby is a popular aquarium fish owing to its general hardiness, attractive appearance, and abilities in picking ectoparasites off of other fishes.

Size and Appearance

Neon gobies are small and typical gobiioid in shape. Most Elacatinus spp. are less than 5cm (2 inches) total length. Neon gobies are black overall with a neon blue stripe extending from front of eye to the base of caudal fin.

Broodstock Care

Omnivorous and hardy they will do well in nearly any species-only or reef aquarium situation, but due to their size should not be kept with larger predatory fishes. Neon gobies do best in water temperatures below 26.5 decrees C (80 degrees F). Foods should include a variety of grated frozen shrimp, squid and fish, as well as commercial gelatin or pellet diets. Multiple feedings daily will condition neon gobies for spawning.

Pair Formation

Hermaphroditic sexual patterns are common in the family Gobiidae. I am not aware of a definitive classification of Elacatinus oceanops, but experience in our lab suggests that they are sequential hermaphrodites rather than simultaneous hermaphrodites.
Males are often larger and more slender. Females will possess a swollen abdomen, particularly when ripe with eggs.

Neon Gobies may be kept as groups of 6 or more individuals when provided with sufficient hiding spots, as these gobies can be quite quarrelsome. If they are to be kept as a pair, they should be observed closely during the first week after introduction. If fighting is excessive, one member of the pair should be swapped until marital harmony ensues. Groups of fewer than 6 individuals are not suggested, as pairs will begin to try to “evict” other gobies in their territory. Larger groups dampen and disperse these aggressive tendencies.

Spawning and Hatching

Spawning can occur as often as every fourteen days with plenty of feeding and warm water conditions. In their natural environment, demersal eggs are laid in small holes and crevices in the reef and under discarded bivalve shells. In captivity, small Tridacna sp shells serve well, as do halved clay flowerpots and short sections of half inch PVC pipe. Both parents tend eggs. Depending on temperature, hatching will commence in 6-8 days. Hatching occurs after dark.

Larval Rearing

Neon goby larvae are slightly shorter and substantially slimmer than clownfish larvae. The larval period ranges from 18-25 days depending on temperature and food type. The first diet is rotifers, followed by Artemia nauplii. The transition period is variable between these foods. Elacatinus larvae can be transitioned to Artemia as early as day 6, and while growth is more rapid, mortality is often high. Waiting until day 12-15 to begin Artemia feedings will delay metamorphosis by a few days, but will also significantly increase survivorship. We have successfully reared batches of neon goby hatchlings through metamorphosis only on rotifers, but metamorphosis took 30-35 days.

We wanted to introduce everyone to a new species we are working with at AZaquaculture - the Pom Pom Crab, Lybia tesselata. Many of you are probably familiar with these odd little crabs, but they are just so unusual we had to share them with anyone who hasn’t encountered them.
Plus, they are SO photogenic!

Probably their most distinctive feature, the feature from which they derive their name, is the appearance of “pom poms” held on a pair of their legs. The pom poms are actually a pair of anemones from the Genus Bunodeopsis. Pom Pom crabs use these stinging anemones as a form of defense, assuming a boxer’s posture in response to threats. Even more remarkable, as the crab molts, these anemones must be moved from the old exoskeleton and mounted to the new chelipeds! No wonder these are a favorite organism for reef aquarium owners.

As you can see clearly in the picture below, this specimen of Lybia tesselata is carrying a fine clutch of eggs along the pleopods. This picture was taken approximately 24 hours after the eggs were deposited. With such odd looking parents, we are all quite excited to start working with the larvae. Check back often, we plan to update with lots of pictures as the project progresses.

Spawning and Rearing the Sonora Goby, Gobiosoma chiquita: Part 2

Larval Hatching and Development

In Section One, we looked at the species characteristics and spawning behaviors of a tough little goby from the Sea of Cortez, the Sonora Goby, Gobiosoma chiquita. In this section we will look at the larval development of this fish and begin to describe the methodologies used in rearing the larvae through to metamorphosis. Subsequent articles will delve into the use of alternative feeds such as frozen microalgae and dry artemia and rotifer substitutes, particularly as this relates to water quality, larval survival and growth, and microbial populations.

Egg Development and Larval Hatching

Hatching occurred on the 9th evening after egg deposition. During development, the eggs turned from a milky opaque to a transparent membrane, which surrounded an easily-visible larvae. Silvery eyes became apparent 1-2 days before hatch. The first hatch was allowed to occur naturally and began 2 hours after the lights went out. All larvae were hatched within 20 minutes, no doubt due in part to the vigorous fanning provided by the male immediately before hatch began. This first hatch was siphoned through a 3/8” piece of silicone tubing into a 10-gallon larval tank. Subsequent larval collection was made much easier with the discovery that hatching could be induced anytime in the afternoon that hatching was scheduled. By exposing the eggs to bright light, (2- 40 watt fluorescents, 1 foot away) and swishing the nest back and forth in water for about 10 seconds, the larvae would begin to hatch within a few minutes of treatment when placed into a suitably dark rearing tank. Using this technique, it was possible to hatch the nests remotely in the larval rearing tanks and avoid the tedium and trauma of trying to catch all of the larvae in the parental tanks. Although the male goes into a frenzy when his nest is removed, when it is replaced 30 minutes later, he immediately calms and resumes his nest tending duties without hesitation. In one case both the male and an overly anxious female swam into the shell and began to spawn in mid-water as the shell was lowered back to the bottom of the tank.

Early Larval Rearing

There is only one word to describe the larvae of Gobiosoma chiquita-Hardy! Within moments of hatch and siphoning, the first larvae were already feeding aggressively on rotifers. Sonora Goby hatchlings are 2-3 mm long with slender bodies and protruding silver eyes. They are not nearly as robust as clownfish, instead more closely resemble the larvae associated with the pseudochromids. They are immediately active and hungry after hatch, taking rotifers with much more skill and accuracy than a clownfish of comparable age. Most bellies can be seen turning silver and bulging with the newly consumed rotifers only 10 minutes after hatch.

For these rearing experiments, several variants of the greenwater technique were utilized. Relatively low densities of larvae (10-20/gallon) were maintained with 10-15 rotifers/ml and either live or frozen microalgae was added directly to the rearing tanks to keep the rotifers enriched and reproducing. There were several advantages to this form of larval rearing in a classroom environment. First, by having a continuously reproducing colony of rotifers in the tank, there is less worry of insufficient prey items in the tank for the larvae to consume. This became especially important on the weekends when 4 or more harvests of rotifers each day would be inconvenient to say the least. Using this technique, simply adding algae once in the morning assured that a supply of nutritious rotifers would be available for the larvae all day. In addition to the advantage of continuous food supply, utilization of live microalgae also serves as a water conditioner to some extent, utilizing the wastes of the larvae and rotifers for their own metabolism.

Because the exact nutritional requirements for this species were unknown, a variety of microalgae species were utilized as rotifer food in order to provide HUFA and EPA profiles that were as diverse as possible. The hatches were split between two tanks so a variety of rearing methods could be tried for each group. Live Tetraselmis and Nanochloropsis were added at least once per day in one tank, which received only live microalgae. In a separate tank, only frozen Isochrysis, Tetraselmis, and Nanochloropsis species from Reed Mariculture were regularly added, as was a small dose of astaxanthin, a pigment believed to aid in oxygen transport and increase survival in clownfish larvae.

Our next section will cover the effects of these various rearing methods on factors such as water chemistry, bacterial levels, and most important, larval growth and survival.