Wrasse (Pseudocheilinus hexataenia), and the Hawaiian Neon or Four-Line Wrasse (P. tetrataenia)\ several smaller species from the genus Halichoeres, such as the hardy Yellow or Golden Coris Wrasse (//. chrysus)\ and the fairy wrasses (genus Cirrhilabrus). Fairy wrasses (sometimes called social wrasses) should be kept in groups consisting of a single male and several females. CLOWN FISHES AND DAMSELFISHES. Clownfishes and damselfishes (Pomacentridae) are often the first fishes kept by a beginner. They are hardy and beautiful and will accept a variety of foods. There is so much interest in clown-fishes that I have devoted an entire section to them (see pages 204-214). Damselfishes that do not associate with anemones occur in many reef habitats.
Pomacentrids are generally territorial species. To minimize disputes, keep only one kind of damselfish per tank. For some, such as the "humbug" damsels in the genus Das- The Mandarinfish (Synchiropus splendidus): exquisite colors cyllus, if you keep several individuals of the same species together, each fish must be provided with its own cave or coral head. This spot will be vigorously defended by the resident damselfish, even unto death.
Perhaps the most popular of the damselfishes is the Blue Devil (Chrysiptera cyanea). This fish can be kept in groups, if one pays attention to sex ratios. On the reef, its natural grouping is a single male and several females and juveniles. Overall body color of both sexes is a stunning electric blue. Females and juveniles have a black spot on the posterior base of the dorsal fin and colorless tail fins. Males lack the black spot and have bright orange-yellow tails. This is one of the few damselfish species that display obvious external sexual differences. In the Philippines and Japan, the male Blue Devil lacks both the black spot and the orange tail.
Chromis are damselfishes that form shoals in open water over reefs, where they feed on plankton. An excellent choice is the Blue-Green Chromis (C. viridis), a native of Spotted or Psychedelic Mandarin (.Synchiropus picturatus)
but a species that does best in a well-established aquarium.
never stock more than one male mandarin per aquarium.
Red-lipped Blenny (Ophioblennius atlanticus)
Canary Blenny (Meiacanthus ovaluensis)
Saber-toothed Cleaner Mimic (Plagiotremus rhinorhynchos)
DRAGONETS. Only two attractive dragonets are commonly imported for the aquarium. Both are bottom-dwelling fishes, with docile habits and exquisite coloration. The Mandarinfish (.Synchiropus splendidus) and the Spotted Mandarin (Synchiropuspicturatus) are ideal specimens for the reef tank. In all dragonets, the male can be distinguished from the female by the greatly elongated first spine of the dorsal fin, and his larger size. One can keep mandarins of the same species together as trios consisting of one male and two females, and one can keep the two mandarin species together, but one should never put two male mandarins of the same species together in the tank. They will fight until one is killed. Mandarins are seldom bothered by other fishes, perhaps because they are poisonous if eaten. Its gaudy coloration lends credence to this supposition. Mandarins feed on copepods and do best in a well-established aquarium. They often starve in new reef tanks and are not for beginners.
RLENNIES. Combtoothed blennies, typified by the Red-lipped Blenny (Ophioblennius atlanticus) from Florida, and the Bicolor Blenny (Ecsenius bicolor) from Indonesia and Australia, feed largely on microalgae. Either species will even eat "red slime" algae, which many other fishes dislike. The Bicolor Blenny is usually dark brown with an orange abdomen and tail, and the Red-lipped Blenny is brown, with distinctive bright red lips. "Eyelash" blennies (genus Cirripectes) also help rid the aquarium of microalgae. They can be recognized by their cirri, which resemble eyelashes.
The saber-toothed blennies do not feed upon algae, but rather upon small bottom-dwelling crustaceans. They swim actively, largely free from fear of predators, because they all have poisonous fangs. Any fish foolish enough to grab one of these blennies will have the inside of its mouth bitten painfully and repeatedly, and will usually spit out the feisty "meal." This trait is used only in defense, however, and the blenny will not bite other fish unless harassed. Saber-
Chapter Ten 245
toothed blennies of the genus Meiacanthus are also called lyretail blennies, because of the shape of their tail. The two saber-toothed blennies most often available to aquarists were once considered subspecies of the same species, M. atrodorsalis, but are now viewed as distinct. The Canary Blenny, M. ovaluensis is bright yellow and is found only around the Fiji Islands. The more wide-ranging M. atrodorsalis is baby blue with a pale green tail and has a black line running through the middle of the dorsal fin and continuing through the center of the eye. It is given a variety of common names in the aquarium trade, including the especially confusing name Eyelash Blenny. Probably because of their poisonous fangs, the color patterns of many of the saber-toothed blennies are mimicked by other fishes, which thereby gain protection from predators.
Another case of mimicry in blennies is well-known and involves two undesirable members of the saber-toothed blenny clan. Plagiotremus rhinorhynchos and Aspidontus tae-niatus both mimic not only the coloration but also the movements of the cleaner wrasse, Labroides dimidiatus. When an unsuspecting fish approaches one of these mas-queraders expecting to be cleaned of parasites, the blenny instead takes a bite from its unfortunate victim. Ironically,^. taeniatus has actually been observed receiving the services of the same cleaner wrasse that it mimics. Some observers also report them feeding heavily on tubeworms and fish eggs. JAWFISHES. Jawfishes are thought to be related to the basslets, but their classification is still being debated. They are excellent aquarium fishes, although inclined to be jumpers. There are jawfishes that grow much too large to be included in a tank with invertebrates such as shrimps, but these are rarely available, owing to their drab coloration or large size or both. New species are being discovered all the time, but they are rarely imported. All require a deep layer of substrate composed of particles ranging in size from grains of sand to small pebbles in which to dig their characteristic
Purple Firefish (Nemateleotris decora): a shy but elegant fire goby and ideal choice for the quiet Indo-Pacific reef.
Common Firefish (Nemateleotris magnifica): best kept singly or in mated pairs, without overly aggressive tankmates.
246 Natural Reef Aquariums
Golden-headed Sleeper Gobies (Valenciennea strigata): live in pairs and can be a challenge to keep well-fed.
The Signal Goby (Signigobius biocellatus): a fish that appears to mimic a crab and that will perish if separated from its mate.
burrows. Further, they cannot be kept with large anemones or other stinging cnidarians, because these will eventually catch and eat the jawfish. So why keep them at all? Simple: there is nothing as charming as a group of jawfishes, each hovering just above its vertical burrow, with large, expressive eyes alert to every movement. Each fish builds itself a pile of shells and gravel at the entrance to the burrow, and each spends quite a bit of time raiding the pile of its neighbor.
There are two species of jawfish collected for the aquarium. One of these, the Blue-spotted Jawfish (Opistognathus rosenblatti), endemic to the Sea of Cortez, is infrequently seen and should not be kept in groups. Far more readily available is the Yellow-headed Jawfish (0. aurifrons) from Florida and the Caribbean. Yellow-headed Jawfish can be kept singly or in groups (a group is more fun to watch) in any size aquarium that will accommodate the number of fishes desired. They will excavate vertical burrows in the substrate, about twice as deep as the fish is long. They feed on planktonic organisms snatched from the water column and accept a variety of fresh and/or frozen foods, such as adult brine shrimp, mysis shrimp, bloodworms, and black-worms. Jawfishes are mouthbrooders, with the male carry ing the eggs until they hatch, and they have spawned and been reared successfully in captivity.
GOBIES AIMD DARTFISHES. The goby group contains the greatest number of species in tropical seas. Virtually all gobies are peaceful, small fishes that feed on small benthic or planktonic invertebrates. Rather than attempt to describe all the gobies that one might find in aquarium shops, I will mention one or two representatives of each of the groups into which the goby clan is divided. Ichthyologists have grouped gobies into two families, but for aquarium purposes, I will consider five artificial groupings.
Family Microdesmidae, the dartfishes, includes two aquarium groups — fire gobies and torpedo gobies. Certainly the most familiar of these are the fire gobies. The Common Firefish (Nemateleotris magnifica) is found in several locations in the Indo-Pacific region. It has a cream-colored body, with a brilliant flame red tail, and hovers in midwater with its elongated dorsal fin held erect. Among the torpedo gobies, the Blue Gudgeon (Ptereleotris het-eroptera) is typical. It is an elongated species, shaped like a torpedo, and is solid baby blue with a single black splotch in the fork of the tail. This species will spend more time
out in the open if kept in a group. Singles often hide. They do not squabble among themselves, as is sometimes the case with the firefish. The Blue Gudgeon is a good jumper; cover the aquarium carefully.
Among the Gobiidae, or true gobies, we find, for aquarium purposes, three subgroups: a huge general grouping of goby species, the signal gobies, and the fascinating prawn gobies.
The Neon Goby (Gobiosoma oceanops) was among the first marine fishes to be spawned in captivity. Today, thousands of them are hatchery-produced. Just over an inch in length, black in color with brilliant blue and white horizontal stripes, the Neon Goby is at home even in a small Rainford's Goby (Amblygobius rainfordi): an endearing sand-tank. Pairs can be obtained by keeping a group of juveniles sifter and just one of a huge array of fascinating gobies, together and allowing them to pair off as they grow. This species is a cleaner. Related species, the Lime-striped Goby they feed. Interestingly, these gobies are known to commute. multifasciatum) and the Red-headed Goby (G. punctic- nicate with each other via signals produced by the mouth.
ulatus) are also available as captive-propagated specimens.
Since ichthyologists have reclassified this group, Valencien-
Much larger than the Neon Goby, the 6-inch Golden- nea is no longer technically a "sleeper" goby (Family Eleotri-
headed Sleeper Goby (Valenciennea strigata) lives in pairs dae). Perhaps a suitable new common name would be in a cave that is constructed by the fish under a rock or other Golden-headed Talking Goby, in honor of their communi-
structure. Older specimens (both males and females) de- cation capabilities.
velop long filaments
Signal Gobies, which are closely related to Valencien-
extending upward nea> may also signal to each other with their mouths, but from the anterior end that is not where the common name comes from. The huge of the dorsal fin. eyespots on the dorsal fins inspired the name Signal Goby
These gobies (as well for the single species Signigobius biocellatus. This goby ap-
as several other parently mimics, of all things, a crab. When threatened,
Valenciennea species the goby extends its dorsal fins to display its eyespots, which, that are imported together with the dark blue pectoral and pelvic fins, are in-
from time to time) tended to give the impression of a large, aggressive crab. The constantly dig in the goby even mimics the sideways movement of a crab. On sand, "chewing" the the reef, Signigobius is usually found in mated pairs and grains to obtain small should only be kept as such in the aquarium. Deprived of
Yellow Watchman Goby (Cryptocentrus cirictus)
crustaceans and its mate, a solitary individual will soon die. These gobies sort worms upon which the substrate to obtain food, but will also take food from
248 Natural Reef Aquariums midwater. They are sometimes imported from Australia, but are never common. Both the Golden-headed Sleeper and the Signal Goby ought to be regarded as species requiring experienced care, as many tend to starve to death in smaller systems without sufficient fare to forage out of the substrate.
The remaining group of gobies demonstrates one of the most remarkable adaptations to be found in the sea. These are the prawn gobies, of which there are several species. I will describe only one, the Yellow Watchman Goby (Cryp-tocentrus cinctus), which is yellow in color with blue dots all over the body. Watchman gobies all have large eyes that are located high on the head. The coloration and appearance of this goby is enough to make it attractive to the aquarist, but the relationship that these gobies have with certain species of prawns (actually alpheid shrimps) is truly amazing.
Prawn gobies live in areas of loose rubble, sand, and gravel, but are unable to dig a burrow into which they can escape from predators. That duty is carried out by the prawn, which has specially modified claws for digging. A prawn and a pair of gobies may share the same burrow, or a 1 v - v '
single goby may occupy the burrow, but the prawn is al- ~ - ^ *
ways present. The goby feeds on small organisms exposed by the excavations of the prawn. So what does the hard-working prawn get from the association? A pair of eyes. The prawn is nearly blind and thus cannot see the approach of
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