Monday, March 30, 2009

Reproductive Assistance for Imperiled Native Fishes

To perpetuate the species ----

Reproduction is a critically important and very complex topic with regards to the study of fishes. Fishes have such a diversity of strategies for sexual reproduction - just as diverse as the many aquatic environments that they inhabit.

Think about attempting to summarize the reproductive strategies for the 28,000 living and described species of fishes -- an overwhelming task. This is why the formulation of an ecological and ethological classification system for reproductive strategies was developed by Eugene Balon (summarized in Chapter 9). This classification reduces the diversity of fishes to 32 different guilds and is attractive to students of Ichthyology.

In our region of the US, many agencies are attempting to restore habitats and populations of rare fish species. One non-profit organization, Conservation Fisheries, has taken the reproductive process into the lab and invented systems to breed rare fishes in captivity for eventual release to former habitats.

Take a look at their newsletter to see the progress they have made with many obscure fish species. For many rare species the only way to study their biology will be to raise them in captivity.

Photo of the Laurel dace (Phoxinus saylori) described by Christopher Skelton in 2001.

Wednesday, March 25, 2009

Freshwater Fishes

Next week we will begin introducing you to the 26 families of Freshwater Fishes that you need to know. Some you already learned in our lessons on Marine Fishes. However, our expectations will be a little different as we concentrate on regional fishes.

You will identify many fishes to species. You will be given a jar of unknown fishes to correctly identify by use of dichotomous keys and other descriptions. By the end of April you will collect fishes from two local streams and should be able to identify the fishes in the field by sight.

So continue to sketch and photograph fish body forms and identifying characteristics. Photograph specimens and zoom in on the unique identifying characteristics. A picture is worth a thousand words and there is no substitute for discovering and describing these for yourself. Quiz each other on new specimens. The more unknown specimens you examine, the more your confidence will grow.

Only 7 lab periods until our field trips -- will you be ready?

What is this fish? Class? Order? Family? Genus? Species?

Tuesday, March 24, 2009

Don't confuse these elongate fishes!!

These three families are often mistaken by Ichthyology students on Lab practical exams.

In the photo on the top the fish the long dorsal and anal fins run confluent with the caudal fin.

In the second photo the fish has a larger pectoral fin. The families are closely related; however the fish tend to be larger and attain lengths of 150 cm.

The fish in the bottom photo have a very long and well spined dorsal fin that runs the entire length of the body and if they have pelvic fins they are very small. The dorsal fin is twice as long as the anal fin.

In what families do these fish belong?

What Order of Fishes is this?

Here's a fish to consider. This species if found in coral reefs and seagrass beds of the Indian and western Pacific oceans.

Does it look like any fish that you have seen?

First think about what is remarkable about this fish. Well, consider their strange body shape and swimming habit: the body is encased in an armor of thin, transparent plates; they swim in synchronized groups, each fish in a vertical position with the snout pointing downwards.

What order of fishes have a similar elongated body as well as NO pelvic fins?

Photo by J. E. Randall

Monday, March 16, 2009

Fishing our tidal rivers in springtime

Fishing anytime from mid-March through May and you are likely to encounter these fish (pictured on bottom), which are anadromous. Averaging around 1 lb., with fish up to 2 lbs. Fish with light spin casting, using very small, brightly colored shad darts, spoons, jigs, or minnow imitation lures. Silver-sided with grayish-green back and a prominent dark spot, followed by a row of lighter spots (especially when fresh - not too evident in photo), on the upper part of the side just behind the gill cover; body long but compressed, asymmetrical top to bottom and in cross section it is wedge-shaped; the lower jaw protrudes significantly beyond the upper jaw when the mouth is closed. you can see this on the illustration. Each scale on the sides has a small dark spot.

If you are lucky you may even catch its larger cousin - in the same genus. What would that be?

Sunday, March 15, 2009



Danionella Dracula

London's Natural museum of History found new species at the bottom of their very own tank. Check it out.

Saturday, March 14, 2009

Giant stingray captured

This giant stingray was captured recently as part of a National Geographic expedition in Thailand. The expedition is part of the megafish project directed by Zeb Hogan, University of Nevada, Reno.

Read more about this giant fish

and watch the video that accompanied the original story that shows the baby stingray along with the big mother.

This is a freshwater stingray and certainly is among the largest freshwater fishes in the world.

Thursday, March 12, 2009

Photos of arowana

There are many photos of the Asian Arowana aka Dragon fish available to browse. You will see why this is such a popular aquarium fish. There are some breeders that provide fish. However, the arowana tends to be overexploited for profit in many areas of the world. The IUCN Red list classifies the Asian Arowana as "Endangered"

Tree of Fish Life

After spring break we will continue to describe a few groups of bony fishes, the Teleostei. These fish are definded by the homocercal tail and the specialized bones that support the symmetrical caudal fin. Hence the name Telesotei which literally means "end bone" The groups that I will use to introduce the Teleostei include the Osteoglossomorpha, Elopomorpha, Clupeomorpha, which are specialized offshoots of the main Teleostei line of evolution. The group in the main line of Teleostei evolution ( i.e, Euteleostei) that I will discuss is the Ostariophysi, a large group of fishes which include the Gonorynchiformes, Cypriniformes, Characiformes, Siluriformes, and Gymnotiformes.

The photo above is the Piraucu (or Arapaima), a member of the Osteoglossidae (bony tongues) that is sometimes referred to as the "Tarpon of the Amazon." Click on Osteoglossomorpha above to take you to a section of the Tree of Life that deals with this fish group. Here you can read more about this group and click on the phylogenetic tree to move up or down and see the interrelationships among the fish groups. I will not present this level of detail for other fish groups because I know you can read those chapters (15 through 26) and investigate further as your prepare your presentations on Fascinating Fishes.

We will then move on to some fundamental questions that people have about fish: What do fish eat? How do fish grow? How do fish breed? How do fish smell? How do fish taste? How do fish see? How do fish hear? How do fish behave in response to environmental change? How do fish communicate?

Thursday, March 5, 2009

Caribbean Reef Fish Identification

Thanks to Bhae-Jin Peemoeller for reviewing many of the families of fishes you might encounter in the Caribbean Reef environments. If you had trouble remembering family names, then you need to review your notecards and photograph files.

Question for today: What is the order and family and common name for the fish in the photo? If you know, click comment below.

There is a free online Reef Fish identification guide. Don Stark, a certified scuba instructor with experience in the Caribbean demonstrates how to identify tropical fish from the Caribbean reef. Learn about identifying markings on fish such as the Peacock Flounder, Rock Beauty and Blue Angelfish. Get tips on identifying Trunkfish, Sand Divers and Chub Fish.

If you don't mind the few commercials, there are wonderful color videos and narrated descriptions of 20 common reef fishes. As you watch the videos you can use your knowledge of fish classification to identify the correct orders and families.

The image gallery and biological profiles sections of Ichthyology at the Florida Museum of Natural History contains additional photographic resources for marine fishes that you need to learn, as well as an excellent field guide to identify common sharks. Browse this site for additional information about Ichthyological Studies.

Enjoy your spring break more by knowing what fish you will encounter.

Wednesday, March 4, 2009

Ancient Creature of the Deep

Our discussion today about the "Discovery" of the coelacanth was a good illustration of the great difficulty of doing scientific investigations of a rare and difficult to find species of fish. You demonstrated a good aptitude about hypothesizing explanations. As we learned as our discussion proceeded, the study of the coelacanth proceeds over many decades to further uncover facts about this interesting and ancient fish.

The story is more fully told in books, websites such as DINOFISH, and the PBS special Ancient Creature of the Deep. I encourage you to learn more and take the quiz posted at the Ancient creature of the Deep site.

Two great books that tell the story are A Fish Caught in Time: The Search for the Coelacanth by Samantha Weinberg (New York: Harper Perennial, 2001) and The History of the Coelacanth Fishes by Peter Forey (New York: Chapman and Hall, 1998).

Picture is worth a thousand words; Video clips, priceless

I am just amazed by how a short video clip can illustrate the fascinating aspects about fishes.
The web site has a large collection of short videoclips on fishes which I highly recommend as you continue your studies of fishes. Supplement your lab work sketching new fishes and their distinguishing characteristics with taking close up photographs of key characteristics or whole fish photos. Then explore the life of the fish more deeply by finding photos and video that illustrate the role of the fish in the ecosystem.

I suggest you browse the short video on the Picasso triggerfish -- which illustrates the feeding and cloud of sand flowing out the gill openings.

Tuesday, March 3, 2009

Bizarre fishes from the Deep Sea

Among the deepsea fishes, there is one order called the Lampridiformes, which includes large brightly colored pelagic fishes. There are two extreme body forms, the opahs (Lampridae), and the oarfish (Regalicidae). The oarfish are distinguishable because they are long, extremely attenuated and reach lengths of 8 meters! The anterior rays of the dorsal fin and the pelvic rays are highly modified - you just have to see them to believe it.

Another oddity about the oarfish is that they maintain position vertically in the water column. The link to has a series of video clips to see this rare creature swimming. Note: the oarfishes are likely responsible for many sea-serpent stories.

The opah, or moonfish, is deepbodied and laterally compressed. It is a solitary fish and most frequently encountered in tuna fisheries.

Neither of these families is on your "need-to-know" list. However, when you encounter an unknown fish anywhere in the world, you can use the family key to fishes at FishBase to identify it.