Marine Fishes of South-East Asia. Gerry Allen
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type of teeth, fin-ray counts, etc. The specific name quinquelineatus applies only to a single entity that is distinguished from its relatives by a unique set of characteristics, often including colour pattern. Related genera (plural of genus) are grouped together in a family, whose spelling always ends in - idae. An illustrated list of families is presented on pages 9-18. Worldwide there are about 450 families - more than 300 are represented in Australia and surrounding regions. A group of similar families is placed in one of the 35 orders of fishes whose spelling always ends in -iformes. The highest rungs on the ‘ladder’ of classification pertain to class and phylum. The class Myxini contains the jawless hagfishes and lampreys (no species included in this book); Chondrichthyes contains sharks and rays; and the third class Osteichthyes contains the majority of fishes. All fishes, as do other higher animals including amphibians, reptiles, birds and mammals, belong to the phylum chordata. Therefore, in summary the classification of the Five-lined Seaperch can be represented as follows.
Phylum - Chordata (all animals with notochord)
Class - Osteichthyes (all bony fishes)
Order - Perciformes (most reef fishes)
Family - Lutjanidae (seaperches and relatives)
Genus - Lutjanus (closely related seaperches)
Species - quinquelineatus (5-lined seaperch)
Characters that are most often used to separate species, and often genera, include external features such as the number of fin rays, size and number of scales, ratio of various body proportions, and colour pattern. For higher classification at levels above genus internal structure, particularly those pertaining to skeletal elements, are often indicative of relationships.
Many species previously unknown to science have been found in our region over the past few decades. When a new fish is discovered it is given a scientific name by the researcher who formally publishes a detailed description in a recognised scientific journal. Scientific names are frequently descriptive. For example quinquelineatus is Latin for five lines and is therefore appropriate for the Fivelined Seaperch (see Pl. 42-7 in species section). New fishes are sometimes named after the locality from where they are collected, for example japonicus (Japan) or novaeguineae (New Guinea). A third category of specific names are based on the names of people, often the person who first discovers the fish (respectable researchers never name fishes after themselves). Fishes named after a male end in - i, those after females in - ae.
PRESERVING FISHES
It is sometimes desirable to preserve specimens, particularly if a positive identification by museum authorities is required. Also small, unusual or rare fishes can be kept as curios or as teaching aids for children. The recommended method of preservation in any case is exactly the same one that is employed by fish biologists in museums. The basic ingredient is full strength formalin which can be obtained from a pharmacy. The preserving solution is made by diluting one part of formalin with nine parts of water. The fish should be fully immersed in the solution. If larger than about 15-20 cm a slit along the side of the belly will facilitate preservation of the internal organs. For long term storage it is desirable to transfer the specimen to a 70 per cent ethyl alcohol solution (70 per cent ethanol, 30 per cent water) after the fish is fully fixed in formalin (i.e. after several weeks). However, the fish may be held in the initial formalin solution for several years without deleterious effects.
Unfortunately colours fade rapidly in preservative. Therefore photography (see below) is a valuable method of accurately recording the colour pattern.
SENDING SPECIMENS
TO THE MUSEUM
Although most of the specimens in the reference collections of the various museums around Australia and South-east Asia are collected on special expeditions by museum staff, occasionally valuable fishes are donated by the public. Also it may be desirable for people living far from their local museum to send specimens in for identification, particularly if the fish in question is suspected to represent a new record for the area or perhaps is very rare. Also members of the public may have the opportunity to collect fishes in remote areas that are not easily reached by museum scientists. For example, several years ago, a medical officer aboard an experimental offshore drilling platform obtained a valuable collection of deep reef fishes on Australia’s North West Shelf that were accidentally captured when the drill was brought up from 120 m depth. In this case none of the fishes were recognised by the crew which included several anglers. The specimens were wisely preserved and sent to the Western Australian Museum. Several species from this collection proved to be previously unknown to science.
Specimens can easily be sent to museums via parcel post if first properly preserved (see above section). They should be removed from the preserving solution, rinsed, and wrapped in moist cloth (cheesecloth is ideal) or newspaper, then sealed in several layers of plastic bags. The bags can then be posted in a well padded cardboard box. In Australia fishes can be sent to any of the following institutions depending on their state of origin: (1) Department of Ichthyology, Western Australian Museum, Francis Street, Perth, W.A. 6000, (2) Department of Ichthyology, Northern Territory Museum, P.O. Box 4646, Darwin, N.T.0801, and (3) Department of Ichthyology, Queensland Museum, P.O. Box 3300, South Brisbane, Qld. 4101.
FISH PHOTOGRAPHY
Nearly everyone carries a camera on fishing and diving expeditions these days. Good photographs can be valuable in determining the identification of a questionable fish, particularly if the catch has already been eaten. Anglers frequently rely on hastily taken snapshots in order to later identify their catch. Their usefulness is sometimes diminished because little care was taken in preparing the fish. The following steps will ensure the photos are of good diagnostic quality: (1) The specimen should be photographed when fresh as live colours fade rapidly after death. (2) An attempt should be made to spread out the fins. With small fishes you can hold the fins erect with sewing pins on a piece of flat styrofoam or cardboard. (3) Wet fish should be blotted dry with a cloth or paper to prevent harsh glare when photographed. (4) The specimen should be placed on a suitable contrasting background and photographed as close as the lens will allow for sharp focus, attempting to fill the frame. (5) It is helpful if a ruler or some other object of known length can be placed besides the fish when it is photographed in order to determine its length later on.
Underwater photography is a fascinating hobby and will add a new dimension to your diving activities. Fish photography, if done on a regular basis, is an excellent method of learning the fishes of an area. Most beginners start out with a Nikonos or one of the relatively inexpensive automatics in a perspex housing. However, to obtain high quality fish portraits it is advisable to use an SLR camera housed in a special case made of perspex or aluminum alloy. In addition, strobe lighting is a must. The cost of the basic outfit ranges from about $3,000- 5,000, so only the serious photographer will consider this alternative. Even for accomplished divers it requires much practice and patience before good results are obtained. The combination of a moving subject on variable backgrounds present a great challenge.
Diver at work, Madang, Papua New Guinea. Underwater photography is the best way to record the fantastic range of colours shown by coral reef fishes. (R. Steene)
DANGEROUS FISHES
The region’s seas are generally safe for normal swimming and wading activities, but there are a number of fishes potentially capable of causing injury. They can be divided into several broad categories including species that bite, sting, or which may cause poisoning if consumed.
Biters - first and foremost in this category are the whaler sharks and their relatives (Plates 1 to 3). In addition there are a number of smaller reef fishes which, although they pose no threat to swimmers, can inflict painful bites if handled carelessly