March 2007 Contents

• Upcoming Events
• Fish Morphology by Bill Cline

Our thanks to Bill Cline this month for hi

s notes on Fish Morphology from his presentation to the club.

SDTFS, C/O Charles Pratt
2545 Ridgeway Dr. # B
National City, CA 91950

or you can pay them BEFORE the auction on Sunday night.

President's Message

The two annual SDTFS auctions require a great deal of work from a lot of people. Let me thank all of you who will be involved in the auction Sunday night for your hard work and dedication to the club.

Upcoming Events at SDTFS

March 11, 2007- Spring Auction - Note: This is a change from April for 2007 only. This is because the April meeting is on the 8th, which is Easter, and we anticipate a lower turnout, so have moved the auction up a month.

Auction Instructions

Buyers

Members have been assigned permanent numbers. Obtain your pie plate with the number at the registration table. Non members will be assigned a number at the registration table. Hold your number up high when you bid.

If you win the bid the item you bought will be delivered to you immediately and you will initial a receipt. Pay when the auction is over. This means you may want to bring styrofoam boxes or coolers to put your fish in after you receive them.

Sellers

You must be a member to sell. You can join on the same night you sell. Download a membership application here

All sellers fill out a sellers sheet which can be obtained here, or at the registration table. Number all your bags of fish and other items for sale with your member number followed by a dash and the item number, starting with 1. As an example if your member number is 173 and you have five items to sell your first item would be 173-1 and your fifth item would be 173-5. If you do not know your member number you can find it at registration at the meeting.

Also on your bag put your name, phone number and the number and type of fish.

Hand the sellers sheet in at the registration table.

Place your items for sale all together and in numerical order on the auction tables. They will be auctioned in numerical order.

See the main web site for meeting dates for the rest of the year.

Fish Morphology

Bill Cline

Body Shapes

Actually, Morphology is a bad name for this class. Technically, morphology is the study of plant’s or animal’s form and structure, without regard to their function. I want to include their function. As long as you believe in evolution, different shapes are easy to explain (of course....if you don’t believe in it, they are even easier to explain). Lake waters are much more still than river and stream waters. Many people would think that would be a cause of great evolution into specialized lake types, but the large majority of lakes only have a natural life of 1 or 2 hundred years....not long enough for any kind of evolution (due to eutrophication - the gradual silting in due to salts and nutrients, and due to floods causing the washing away of natural dams). The rift lakes of Africa are an exception, having been around for thousands of years. The evolution in them will keep biologists busy for a hundred years. When they were new, they as well as all other lakes, were settled by generalized fishes from the streams and rivers feeding into them. Where speed is important to fish, like fast-flowing streams, and open-watered lakes, cigar-shaped bodies prevail. Where there are lots of obstructions and hiding places (plants, fallen trees, rocks, coral, etc), eels, heavily bodied fishes, and fishes with pancake-shaped bodies tend to prevail.

Probably the most obvious place to start this discussion is with body shapes....since that is the first thing we see when we look at a fish. In general, fish are categorized into 6 shapes, though there are too many exceptions to count.

Let’s talk about 1) Rover-Predators first. These are the streamlined fish, with a cigar-shaped body, a pointed head, with a mouth at the tip, a narrow caudal peduncle (the part just in front of the tail fin), and a forked tail. Having the fins evenly distributed about the body gives them stability and maneuverability. These fish are either constantly moving, looking for food, or swimming in place against a strong current, waiting for the rushing water to present food to them (like trout stationed just downstream of a boulder). They have many of the other characters which give speed as well; when you look at a cross-section of the fish, it is either round like an egg, or elliptical like an egg (depending on how you hold the egg), the body is bigger around in front than it is in the rear, nothing sticks out from the body to resist the water, the eye-surface is flat rather than bulging, gill-covers are close-fitting, and the scales are tiny. The paired fins are flattened against the body, while swimming fast, and in some members of the tuna family, even the dorsal and anal fins can collapse into slots on the body, so they offer little resistance. The fastest fish is a marlin, which has been clocked at 60 mph, but speed is directly related to length, so the mackerel, at 11 mph is no slouch. The Brown Trout is also pretty fast at 8.2 mph, as is the Northern Pike at 7.6. An adult goldfish (not a fantail) surprises me at 5.8. But since the average man walks at 4 mph, I’m a bit disappointed in the stickleback (2.6) and the sprat (2.3). Because of their size, I can forgive the goby (Gobius) at 1 mph, and the blenny (Zoarces) at .8. Some of the many aquarium fishes with this style of body include Danios, White Clouds, non-heteromorpha Rasboras, Neons, Australian Rainbowfish, Cherry Barbs, Bloodfins, Pink-tailed Chalceus, Daces, Rummy-nosed Tetras, Hemiodus, Loreto Tetras, Black Neons, Bala Sharks, Blue Tetras, Pencilfishes, Pyrrhulinas.

The next body type is 2) Lie-in-wait Predators. They usually eat other fish, and have a body designed for ambush. They have a cigar-shaped body, much like rover-predators, but the anal and dorsal fins are larger and closer to the tail, where those fins serve a more important purpose of providing instant propulsion, at the cost of providing less stability. The head is usually flattened and pointed, with a large mouth and lots of pointy teeth. They are hard for prey fish to see because they not only have cryptic coloration (their color is the same as the rest of their surroundings), and because they hide behind or within other objects, but also because when they face a prey, they are as hard to see as a cigar would be, if it was pointed right at you. The prey wouldn’t see the large body hidden behind the head. Typical of this group would be barracudas, gars and pikes, but in tropical fish stores, the African Pike Tetra (Hepsetus odoe), South American Barracuda Tetras (Acestrorhynchus), Pike Characins (Boulengerella and Ctenolucius), Belonosox, Epiplatys and Pachypanchax (killis which prey either on fry or bugs and fry), and Pike Characins (Phago).

The next group is 3) Surface-oriented Fish. This group usually has a small size, reflecting the kind of food they’re often limited to; insects, plankton and small fishes. They have an upward-pointing mouth, a head flattened from top to bottom, large eyes, and a dorsal fin placed near the tail. A lot of the fish in this group are adapted not only to the food found in the top few inches, but they are also adapted to the high level of oxygen, which may only be found in the top few millimeters. Lots of surface-oriented fish are found in low-oxygen waters, where the surface is the only place they can live. Some however, like halfbeaks, come from saltwater areas, where there is no shortage of oxygen in the lower levels - they’re just adapted to the food source. The saltwater flying fish has a different cross-section from the normal fish. They have a flat bottom and are rectangular in cross-section. Their flat bottom makes a planing surface to help them take off into flight. There’s an awful lot of aquarium fish in this group, including most of the aquarium livebearers (poecilids and jenynsiids), flying barbs (Esomus), archer fish, penguin fish, Celebese rainbow fish (Telmatherina), most anabantids (Bettas and gouramis), halfbeaks, four-eyed fish, hatchetfish, elongate hatchetfish (Triportheus, which is closer-related to a penguin fish), most of the killifish, Bedotia of the atherinids, glass barbs of the genus Chela, blue and Barber’s tetras of the genus Mimagoniates, and the tetra Stevardia (formerly Corynopoma).

This brings us to our next main group, 4) The Bottom Fish, but it is broken up into 5 sub-groups. The first of these sub-groups is the bottom rovers. These fish have a typical rover-predator like body, except that the heads tend to be flattened, the back tends to be humped, and the pectoral fins enlarged. Included are just about all the catfish (including those with sucker-mouths), sturgeons, and some of the sharks. Many of this group (except the sharks) have small eyes and well-developed barbels (with tastebuds) to find prey in murky water or at night. The bottom-clingers are usually small fish. They have similar bodies to the previous group, in that they have flattened heads and large pectoral fins. Many of them have pelvic fins fused into suction cups (gobies and clingfishes), to hold them in place against swiftly flowing water. Skulpins (Cottidae) have pelvic fins which are separate, but are close-fitting enough to serve the same purpose. Bottom hiders look much like the bottom clingers, but without the suction equipment. They must seek shelter under rocks or driftwood, in order to maintain their position in swift streams. If they are in still water, members of this group lie quietly on the bottom. This group includes members from the darters (Percidae), blennies (Blennidae), and a few cichlids (like Steatocranus). Most people are familiar with the Flatfish (flounders, skates and rays). They are actually very different, in that flounders are laying on their sides, while skates and rays are laying on their bellies (we’ll ignore the numerous other major differences). Even with their differences, they’ve still come by the same overall shape, as an adaptation to laying on an open, flat bottom. When these fish lay on the bottom, they are almost impossible to see, especially when they partially bury themselves. The last sub-group of the bottom fishes is the Rattail Shape. Since I expect to be very short on time, I’ll skip this group except to say that they won’t be found in anybody’s tanks. They live on the bottom of deep oceans, and have long rat-like tails, the purpose of.which people can only guess

.

The next group is 5) the Deep-bodied Fish. It is another group which is well represented in the tanks of your local tropical fish store. Their bodies are flattened side-to-side, with a height equal to at least 1/3 of its standard length. Usually, the dorsal and anal fins have a long base. The pectoral fins are usually fairly high on the body, with the pelvic fins straight down from them. They use both these fins, when they put on the brakes. If they tried to brake with one pair or the other, it would be like a skier trying to brake by only turning one ski to the side. If the pelvics weren’t right under the pectoral, the fish would start rolling end-over-end. They usually have a small, protrusible mouth, large eyes, and short snouts. This all makes them well-adapted to tight quarters, such as dense vegetation, coral reefs, or even schools of their own kind. They are also well adapted for feeding on small invertebrates from the substrate (plants, mud, coral) or right out of the open water - they can see the animal right up close and watch it till it goes in their mouth. Though most are adapted to the substrate, some are adapted to open water, where they may present a smaller view to predators underneath. This group would include fresh and saltwater angels, saltwater butterflies, discus, silver dollars, piranhas and many others.

The last group is the Eel-like Fish. How does one describe an eel-like fish other than to say it looks like an eel? Their head may be blunt or wedge shaped. Their tails may be pointed or rounded. Dorsal and anal fins usually have long bases, but not much height. The paired fins, however, if not absent, are greatly reduced. If they have scales, they are usually small and embedded. If one looks at their bodies in cross-section, they may be round or flattened. Although they are very well-adapted to living in crevices and holes in coral, rocky areas, tangles of sunken wood, beds of aquatic plants, or just living in the mud, they are also found swimming in open water (Anguillids). Examples in the aquarium world would include kuhli loaches, weather fish, horse-faced loaches, moray eels, ribbon eels, spiny eels, reedfish, South American and African lungfish, lampreys, knifefishes, and swamp eels (Monopterus and Amphipnous). Whereas the kuhli loaches (Acanthophthalmus) live in the soft mud of slow rivers, the horse-faced loaches (Acanthopsis) live in the gravel bottoms of fast-flowing streams. The main advantage of the first hiding from predators, while in the second case, an advantage of holding the fish in place against the water is added, without using much energy.