Amongst the giddying myriad of nano-sized gobies suited for the home aquarist, few genera exuberates brilliance and mystique quite like Tryssogobius. The genus comprises of delicate dainty gobies, of which seven are scientifically recognized. There are invariably many more waiting to be discovered, but like their prevalence in the aquarium trade, they go unnoticed by even the most seasoned diver. Tryssogobius is a true diamond in the rough, an incognito conglomeration of gobies anonymous. [Photo above of Tryssogobius sarah. Photo credit: Moguri]
Tryssogobius is easily identified by its generic morphology. The members are small, barely exceeding two inches in length and can be recognized by their pearlescent ground coloration. All species possess double dorsal fins, of which the first is elongated and sickle shaped. Despite their characteristic appearances, Tryssogobius is difficult to identify and separate in the field, and the Internet is rife with pictorial inaccuracies. Scientific literature isn’t spared from this plague as well, and we find various inconsistencies with regards to identification and their corresponding traits.
All the species are adorned with blue and yellow stripes on their fins, and although this template is repeated rather closely, careful observation reveals minute differences that are reliable enough to separate the members. This article will hopefully provide a simplified guide to that.
These fairy gobies are not in the strictest sense, reef-dwelling fish. They are fond of sandy substrate littered with rubble and rocky outcrops adjacent to steep reef walls and slopes. Turbid, silty environments with the same penchant for sandy bottoms replete with rubble are also choice habitats. Tryssogobius are relatively deepwater, being found at depths ranging from 80-360ft depending on the species. They are often found hovering nervously in groups over the substrate and are extremely skittish and difficult to approach, choosing to dart into the rubble at the first sign of danger.
The species are primarily distributed around Indonesia, with many species occupying a large sympatric overlap. However, due to the innocuous nature of this species in the wild, coupled with its preference for deep and silty environments, their actual distribution is poorly documented and is likely to be far more extensive.
A handful of species are available to the aquarium trade, albeit rarely and with haphazard appearances. Nearly all are erroneously identified as T. colini, the go to “dumping ground species”, so it may come as a surprise that during the writing of this guide, I struggled to find actual photos of T. colini. Let’s take a look at the species in all their miniaturized splendor.
Tryssogobius colini (Etymology: named in honor of Dr. Patrick Colin, who collected the type specimens)
Distribution: Indonesia and Papua New Guinea.
Tryssogobius colini along with T. longipes were the first two members to be described, resulting in the erection of a new genus. It is remarkably similar to the latter, and almost all other members in this genus. However it can be separated based on the following.
– In T. colini, the first dorsal fin is edged in blue and yellow on the anterior margin. The base is linearly spotted in yellow and emarginated with blue. The first dorsal fin is also falcate, plateauing in a broad tip.
– The second dorsal fin is likewise linearly spotted in yellow at the base. The outer margin is edged in a thick cerulean with a single yellow stripe running equatorially within. The corresponding pattern can be seen on the anal fin. Both fins terminate porteriorly in an oblique angle running in opposite directions.
– The body coloration is pearly silver-white with very faint transverse orange bars behind the operculum. They diffuse posteriorly and become less evident toward the caudal peduncle.
– A zone of yellow spots and stripes are variably present behind the eye.
– The caudal fin is rhomboidal, trimmed on each side with a pair of cerulean margins and a corresponding yellow stripe. A black spot is sometimes seen at the caudal peduncle, which becomes very evident once preserved in alcohol. This however, does not show up well in some live specimens.
Tryssogobius flavolineatus (Etymology: yellow line)
Distribution: Indonesia and Papua New Guinea.
Tryssogobius flavolineatus is easily recognized by its namesake yellow stripe. The following are the ID characteristics for this species.
– The first dorsal fin is weakly edged in blue on the anterior margin. The base is lined in a horizontal yellow stripe, and layered on top with a cerulean stripe of similar thickness. These are never broken or spotted in T. flavolineatus. The first dorsal fin is falcate, and ends with a blunt tip.
– The second dorsal fin is likewise decorated with a single yellow stripe at the base, bordered on both sides in cerulean. The outer margin is edged in cerulean, but the yellow stripe within is broken and dotted linearly. Both dorsal and anal fins terminate in an oblique angle, but never as dramatically as with T. colini.
– The body coloration is pearly silver-white with a faint teal suffusion dorsally. No transverse stripes or bars are present.
– A characteristic yellow stripe runs behind the eye before terminating slightly past the pectoral fin. This is the main and most reliable characteristic of the species.
– The caudal fin is slightly rhomboidal, trimmed on each side with a pair of cerulean margins and a corresponding yellow stripe. An additional yellow stripe runs on the central ray starting at the caudal fin base.
Tryssogobius longipes (Etymology: long fin)
Distribution: Indonesia (Flores and West Papua) and Papua New Guinea.
Tryssogobius longipes is named for its pelvic fins, which, as with all gobies, are fused and cup like. However it is the length in which the name is derived from, and in males these get a little longer than the other Tryssogobius members. In T. longipes,
– the first dorsal fin is not edged in yellow or blue on the anterior margin. The base is strongly striped in yellow, layered on top with a cerulean stripe of similar thickness. This is never broken in T. longipes. The first dorsal fin is sickle shaped and narrowly pointed at the tip.
– The second dorsal fin is strongly marked in a pair of yellow stripes, one running horizontally along the base and the other on the outer margin of the fin. The yellow stripes are weakly edged in blue.
– The body coloration is in the usual pearlescent silver, but a faint tangerine stripe runs equatorially along its entire length, starting from behind the eye to the caudal peduncle. This is the most distinguishable feature for this species.
– The caudal fin is rhomboidal, and is decorated with a pair of yellow stripes running parallel before converging at the terminus. No additional stripes are present on the central rays.
Tryssogobius nigrolineatus (Etymology: black line)
Distribution: Ryukyu Islands, south to Indonesia (Cenderawasih Bay, Raja Ampat and West Papua) and far east to Fiji.
Tryssogobius nigrolineatus is named after the longitudinal black line that is weakly present on the body. This feature is more prominent in preserved specimens, and can be difficult to distinguish in real life. However, T. nigrolineatus is very easy to separate based on its other traits. In this beautiful species,
– the first dorsal fin is edged very weakly in a sliver of yellow and blue. The base is dotted linearly in yellow on a thicker periwinkle edge. The dorsal fin is extremely elongate and falcate, ending with a sharp tip.
– The second dorsal fin is similarly decorated in a broken yellow stripe, dotted along the base. The outer edge is emarginated in periwinkle, with a single yellow stripe running in the middle. The anal fin is marked in a yellow stripe, running obliquely from the corner of the starting edge to the corner of the outermost edge. This stripe is edged on both sides in periwinkle blue.
– The body is in the usual pearlescent silver, with a very faint black stripe of varying intensity running longitudinally. This becomes more evident in preserved specimens.
– The caudal fin is rounded, and is decorated in a constellation of yellow spots on opposite edges and the central rays. The periwinkle blue is not represented by any distinct stripes, but instead suffuses as a light background behind the yellow spots.
Tryssogobius porosus (Etymology: named for its preopercular pores)
Distribution: China and Taiwan.
Tryssogobius porosus is a poorly known species known from China and Taiwan. The species was named after its peropercular and opercular pores that serves to distinguish this from all other members. There are no living images of this species, and aquarists are unlikely to encounter it due to its unusual distribution. Based on a single dead specimen, it appears that
– the first dorsal fin is decorated on the posterior margin with a black and white blotch, and appears to be broadly falcate with a blunt tip.
– The body is decorated in faint transverse yellow bands, with a single yellow stripe on the caudal peduncle. A network of yellow lines appear to be present behind the eye.
– The caudal fin is rounded and decorated in a seemingly random pattern of yellow spots.
Because of the poor quality of the specimen, no live coloration could be discerned, but the species is probably colored in the same pearlescent silver with the usual blue accents on the fins.
Tryssogobius quinquespinus (Etymology: five spines)
Distribution: Papua New Guinea, and west to the Philippines.
Tryssogobius quinquespinus is another lesser-known member known from Papua New Guinea. This species has been photographed in Mactan, Philippines, so the range for T. quinquespinus is definitely much larger than originally thought. This species is unusual in possessing an extremely elongated first dorsal fin, which presumably occurs in males. To identify this species, look out for
– an unmarked first dorsal fin with five spinous rays. This is the only member in the genus to have this characteristic, and is rare even amongst other gobies. The first and second dorsal rays have the propensity to dramatically elongate into a filamentous extension, but this occurs to be inconsistent amongst individuals, suggesting that this trait is perhaps sex-linked.
– The second dorsal fin is unmarked at the base, and on the outer leading edge, a single yellow stripe trimmed in metallic azure is present. The anal fin is similarly marked.
– The body coloration is translucent grey, and a single yellow stripe runs from behind the eye, longitudinally across to the caudal peduncle.
– The caudal fin is forked, with two long filamentous rays extending on opposite lobes. A single filamentous extension is present on the central rays as well. The caudal is marked in the same way as the dorsal and anal fin, with each margin trimmed in yellow emarginated in metallic azure.
Tryssogobius sarah (Etymology: named in honor of Miss Sarah Crow, an aspiring marine biologist)
Distribution: Ryukyu Islands, Philippines, south to Indonesia, Papua New Guinea and Palau.
Tryssogobius sarah is probably the commonest and most widely distributed species in this genus. It is very similar to T. colini and T. longipes, but can be differentiated from the former two by having an unmarked body (diffused orange stripes and horizontal stripe in colini and longipes respectively). The following are the characteristics for T. sarah.
– The first dorsal fin is edged in blue on the anterior margin, and broadly edged in the same shade at the base, where a thin yellow stripe runs unbroken horizontally. The first dorsal fin is sickle shaped and sharply pointed at the tip.
– The second dorsal fin is suffused in blue, with a pair of horizontally yellow stripes running parallel. The exact same pattern is repeated on the anal fin.
– The body coloration is pearlescent silvery-white and completely unmarked.
– The caudal fin is rhomboidal, suffused in blue with a pair of yellow stripes converging at the terminus.
It is unlikely that every species shown here is available to the intrepid aquarist. However, a few species like T. longipes and T. sarah do show up from time to time. These should ideally be kept in a group, in a similar setting that mimics their natural environment. Soft sandy substrate with low lying lose pieces of rubble and rocks are perfect. Being skittish and coming from deeper waters, an initial period of dim lighting would greatly benefit in helping them settle down.
Dither fish of similar stature such as Trimma and Eviota may be housed together, and these slightly more active fish may elicit the Tryssogobius out of hiding. While these fishes are extremely delicate and shy, there is no reason why they won’t be able to thrive in a small and dedicated biotope style display. Feed your Tryssogobius small meaty food like artemia or defrosted and minced mysid shrimps.
Here we are again, at the end of another series featuring fish you probably thought never existed. Now you’re probably feeling compelled to set up a small display to house these pretty little things. Best of luck finding them! Their diamond dusted bodies and sapphire eyes are reasons enough to.