That Fish Blog – Aquarium Advice and Information

Hello, Frank Indiviglio here.

With their ridiculously long “noses” (actually an extended jaw), secretive ways and unique feeding strategies, the elephant-nosed fishes have long been aquarium favorites.  All of the 200+ species discharge electrical pulses from specially-modified muscle cells near the tail. 

The most commonly kept species, Peter’s elephant nose, has been shown to vary the strength, frequency and duration of these discharges.  Doing so helps this nocturnal fish to navigate and hunt in the turbid West African rivers it inhabits.

Using Electricity to Choose a Mate

Recently, researchers at Germany’s Potsdam University have shown that a related species, Campylomormyrus compressirostris, identifies potential mates by the characteristics of their electrical discharges. 

In laboratory tests, gravid females responded to the signals of males of their own species, but ignored those of a closely related fish that shares their natural habitat.  In this way, they are able to locate a mate of the proper species, even when surrounded by similar fishes in murky water at night.

It is theorized that Peter’s elephant nose also uses electricity as a form of communication and mate recognition.  Certainly, watching them avoid obstacles and locate buried blackworms in an aquarium at night, it is easy to see how completely they rely upon their electric-generating system.

Keeping Elephant-Nosed Fishes

Although very popular, elephant-nosed fishes require special care and rarely do well in community aquariums.  I recently set up an exhibit housing a group along with some other of their interesting West African neighbors – butterfly fishes, giant filter-feeding shrimp and dwarf clawed frogs.  Please look for an article on this exhibit and their general care soon.

Please Note:  The “trunk-less” fish pictured with the elephant noses is not the victim of an unfortunate accident but rather a related species, the baby whale or stoneroller, Pollimyrus isidori.  They are also quite interesting and do, if you have an active imagination, somewhat resemble (very!) small whales.  I’ll address them in the article mentioned above.

Further Reading

Belgium’s Africamuseum has posted an interesting article on the Peter’s elephant nose (Note: the photo appears to be of a deceased fish…they are much more attractive than pictured here!): http://www.africamuseum.be/museum/treasures/gnathonemus%20petersii

Please write in with your comments and questions.  Thanks, until next time, Frank Indiviglio.

Hello, Frank Indiviglio here.

Two articles addressing fresh water and marine fish conservation issues were published this week:

Oriental Weatherfishes in Spain

According to an article in Biological Invasions, the Oriental Weatherfish (native to eastern Russia, south and Southeast Asia) is now well established throughout Spain’s Ebro River delta, and has a foothold in the Onyar River as well. This is of particular concern because over 80% of the Iberian Peninsula’s freshwater fishes are already considered to be threatened, with introduced species outnumbering natives in most rivers.

Last year, studies of the eel fishery in the Ebro River revealed that 8.2 tons of non-target fish, representing 17 species, are captured along with each ton of eels (elvers) harvested.  Approximately 40% of these fish perish before they can be released.

Fishes of the Coral Triangle

Reef fishes are becoming increasingly popular on restaurant menus throughout Southeast Asia and mainland China.  Particularly hard hit are species native to the waters bordered by Malaysia, Indonesia, Papua New Guinea, the Philippines, East Timor and the Solomon Islands.  Known as the “Coral Triangle”, this region is home to 75% of all known species of coral.

According to a recent Conservation Biology article, spawning aggregations of local species have declined by 79% in recent years, largely due to over-fishing.  Groupers, 26 species of which are endangered, have suffered the most.  Conservation efforts are complicated by the large number of countries having interests in these waters.

Thanks, until next time, Frank Indiviglio.

For further information on the natural history and captive care of weatherfishes, please see:

http://blogs.thatpetplace.com/thatfishblog/2008/05/22/fish-for-the-cold-water-aquarium-%e2%80%93-the-oriental-weatherfish-misgurnus-anguillicaudatus-the-european-weatherfish-misgurnus-fossilis/

Eileen here. The blind and visually impaired  have greater access than ever before to activities that have been off-limited in the past, but until very recently they have not been able to enjoy the beauty and activity of a colorful aquarium like the rest of us. A group of scientists is working to change this. The Georgia Tech Center for Music Technology is designing what they have dubbed “The Accessible Aquarium.”

The Accessible Aquarium is fitted with cameras and sensors that track the movement of the different colored fish and sends the data back to a computer system. The data is then translated into different pitches, instruments and sounds that change with the speed and movement of the fish. The center is also hoping to be able to apply this technology to venues like zoos and museums as well as aquariums. According to a recent Yahoo! Tech news article, the researchers “wanted to help people with disabilities do something that’s more fun and than functional.”

Georgia Tech Center for Music Technology: http://gtcmt.coa.gatech.edu/

Yahoo! Tech article: http://tech.yahoo.com/news/ap/20081217/ap_on_hi_te/tec_techbit_audio_aquarium

Hello, Frank Indiviglio here.

Sea slugs are shell-less, swimming mollusks that are much favored by marine aquarists for their beautiful colors and unusual lifestyles.  Studies at Texas A&M University recently (December, 2008) revealed just how unusual their survival strategies can be.

Stealing Plant Cells to Produce Food

It has been known for some time that that the emerald elysia, a sea slug native to North America’s Eastern Seaboard, is dependent, in an odd sort of way, upon one species of marine algae (seaweed).  Newly discovered details of its relationship with the algae are startling.  It seems that these sea slugs are unique among animals in being born with at least 1 gene that supports photosynthesis.

However, newborn sea slugs cannot actually harness the sun’s energy and utilize it to produce food, as can algae and plants.  For this they must consume the cytoplasm (internal material) of marine algae.  Within the cytoplasm are organelles known as plastids (chloroplasts), which trap solar energy and convert it into food.  Amazingly, the algae’s plastids continue in this role after being consumed by a sea slug. 

The Switch – Consuming Energy to Producing Energy

The newly discovered sea slug photosynthetic gene seems to be the key factor in allowing this unique relationship to function – without it, the alga’s plastids would not likely survive in such an alien environment.

In essence, the sea slug converts itself into a solar powered, plant-like animal – the only known example of such a phenomenon!  Some marine biologists speculate that, given time, the emerald elysia might evolve into a truly photosynthetic animal.

Something new and unexpected is always popping up in this wonderful field of ours – please pass along your own news tidbits.  Thanks, until next time, Frank Indiviglio.

Background information on the emerald elysia’s unique feeding mode is posted at:

http://sbe.umaine.edu/symbio/

Hey everyone!  Recently I was forwarded this article by a friend that I really found to be a good read.  It almost made me feel like I felt when I read those little paperback serial stories as a kid.  I really can’t wait to hear more about this and see a plethora of photos when they’re available as a continuation about the new things they’ve discovered while compiling the Census of Marine Life.

This short article is another testimony to how big and yet un-explored the oceans of the world still are.  This census is being compiled by more than 2000 scientists from 82 nations and it is to be completed in 2010.  The data will be published in a series of three books after the study has concluded: a survey of sea life, one focusing on the working groups, and a third on biodiversity.  A speck of the newly compiled data on behaviors, new species, and other topics is touched upon by the author of this article and others I’ve seen.  I wanted to make sure the link was blogged so anyone interested can stay tuned for more on the census. 

http://www.coml.org/

http://www.cbsnews.com/stories/2008/11/09/tech/main4586743.shtml