One of the less commonly encountered rays in the aquarium trade, is the eastern fiddler ray, Trygonorhina fasciata. Although it is a ray, it has the general appearance of a less specialized demersal shark, and similarly swims by using horizontal oscillations, rather than by using its 'wings' or 'disc' as would a stingray or a skate. As such it is an interesting animal for those of us who appreciate evolution: after all, rays are,evolved from more typical demersal sharks. What is more, the modern sharks themselves originated as demersal animals; what we think of as classic sharks like 'Jaws', are really atypical and specialized forms themselves.
It's not surprising that fiddler rays are also called banjo sharks; a name that is not inappropriate, because all rays are sharks. Historically they were considered to be members of a grouping of rays called the 'rhinopristiforms', which are the most protomorphic of the modern rays. They still resemble the exquisitely preserved fossil rays of the Jurassic, such as those from the Solnhofen limestone in Germany, which preserved also the bird-like Archaeopteryx - another transitional form.
It isn't yet sure exactly how the 'rhinopristiform' rays are related to each other, or to the other rays. Frustrating though it might be, in such a situation of uncertainty, it is useful to think of them as a hub generating spokes, namely the stingrays, the electric rays, and the skates. Fiddler rays might be a distinct evolutionary lineage from the other, true rhinopristiforms, or sawfish allies. But in any case they are a modern animal that has remained quite similar to the well preserved Jurassic rays.
T. fasciata seldom exceeds 110 centimeters or 44 inches long. As a specimen animal it would surely qualify for the 'tankbuster' category, requiring an unobstructed area of substrate some 4x by 3.5x their total length. Because they are rays, they are routinely described as possessing a disc that is formed by the expansion of their pectoral fins. Although they do, their intermediate bauplan, with a suboval form, makes the word less descriptive than it is for many other rays. Yet they are more rounded and classically ray-like, than are the other 'rhinopristiform' rays
Fiddler rays are denizens of shallow, soft substrate habitats including seagrass meadows. As might be expected they are carnivores that feed on benthic prey - a mixture of crustaceans such as crabs, which comprise their basic diets, together with small fishes, annelids, and mollusks including cephalopods. Their exact diet differs throughout the year and per locality, demonstrating some flexibility and adaptability. Their dietary adaptation may be seen in their tooth rows: they possess an arrangement of blunted teeth in a 'pavement' for grinding and crushing hard prey. Like many other sharks, fiddler rays are opportunistic scavengers, and they are attracted as foragers to the bait placed in traps that are intended for other species.
T. fasciata is an endemic shark from Australian shores, being distributed from from about Fraser Island down to the eastern Bass Strait, which separates Australian mainland from Tasmania. This species is easily confused with its neighbor, the southern fiddler rays, which is distributed yo its south. Needless to say the temperatures of the Bass Strait are scarcely tropical. But further north within its range, the eastern species encounters average summer temperatures of 26 degrees centigrade, dropping to about 21 degrees in the coolest months.
Fiddler rays require an appropriate water temperature and a sand substrate to reflect their sandflat habitat. However they are otherwise hardy and easy to care for, assuming the proper space is available to them, by feeding them meaty foods. They are not aggressive to fish or other small sharks, that are too large for them to dare attempt preying on. The problem is, as with many other 'small' sharks, their expected size.
