That Fish Blog – Aquarium Advice and Information

GloFish are some of the most popular, colorful and controversial fish to enter the aquarium trade in a long time. Their easy care, small size, peaceful nature and neon bright colors make them appealing to aquarists of all ages, but the modifications that cause these bright colors cause some debate among aquarists, scientists and environmentalists alike.

The original “GloFish” were not created for the aquarium trade. They came from a popular fish used in many different fields of research, the Zebra Danio (Danio rerio). Zebra Danios have been used in research for environmental studies, cancer research, genetics, reproductive biology, neuroscience and applications to other fields as well. They even made the trip to space in 1975 on the Russian “Salyut 5” space station. So what makes them such good research subject? Zebra Danios are easy to breed and it only takes hours for the internal organs to develop after the eggs have been fertilized (about 24-36 hours, depending on temperatures and conditions). During this time, it is easy for researchers to monitor the development of the embryo since the “shell” around the eggs is a clear membrane. The eggs can hatch about 12-36 hours after that (again, depending on the conditions). These variable time frames also mean that, while the development is being studied, conditions can be adjusted to slow down or speed up the development, depending on what exactly the researchers are trying to determine. The genetic sequence involving the structure of the Zebra Danio’s DNA and RNA is very well-known at this point and is comparable enough to our own that, by understanding how changes in this structure affect the fish, researchers are gaining more understanding into how changes in our genetic structure can affect our own health.

Originally, GloFish were being developed for two major fields: cancer research and pollution detection. In the late 1990’s/early 2000’s, researchers thought to develop a fish that would change colors when a certain pollutant was found in their water. The thought was to develop a fish that would appear normal in “ideal” conditions but when a specific chemical or type of chemical was present in the water, a “trigger” would be set off to cause the fish to “glow” with a fluorescent protein in their bodies. As a step in this direction, they began to develop a fish that would always have this flourescent “glow” in a reproducible and hereditary way that wouldn’t affect the ecosystem around them. To do this, scientists turned to a fluorescent protein naturally found in jellyfish, corals and anemones rather than potentially harmful chemical dyes. Around the same time, similar projects were using a fluorescent protein to “mark” specific genes that were thought to be a cause or sign of cancer. By pairing the fluorescent protein with the cancer-related gene, researchers could see the fluorescence increase or decrease along with the other gene and see if an increase or decrease in that gene was related to the cancer. Since the genes (and cancers) in these fish behave in much the same was as they do within ourselves, researchers are using this to develop a way to track, diagnose and treat cancer in people. Read More »

 In habits, appearance, and evolutionary history, the African Butterfly Fish, Pantodon buchholzi, is one of the most unusual of all aquarium species.  Yet despite having been in the trade for over 100 years, this “freshwater flying fish” (a misnomer, see below) gets little attention.  Captive breeding is challenging but possible, and its fantastic hunting behaviors are thrilling to observe.  I helped to set up an African Butterfly Fish exhibit at the Bronx Zoo, and was not at all surprised when it became a great favorite.  Most of the visitors I spoke with were astonished to learn that such an “exotic” creature, worthy of a large zoo exhibit, was available at many pet stores! 

Description

The yellowish-green to silvery-tan body is marked with an intricate pattern of speckles and lines.  The huge pectoral fins, reminiscent of those of marine flying fishes, lend an uncanny resemblance to a dead, floating leaf when viewed from above.  Long rays extending from the tail and the pelvic fin add to its remarkable camouflage.

Uploaded to Wikipedia Commons by Toniher

The African Butterfly Fish’s mouth is noticeably upturned, an adaptation for feeding on insects at and above the water’s surface.  Less noticeable is the mouth’s large size and the many teeth it bears; although it tops out at 5 ½ inches, this specialized predator can take quite sizable insects and fishes.

Utilizing its wing-like pectoral fins and unique musculature, the African Butterfly Fish can explode from the water’s surface to snatch low-flying dragonflies, moths and other insects, and to escape predators.  It does not, as far as we know, glide above the water as do marine Flying Fishes (please see photo). Read More »

A few days ago, I came across a curious story in the aquatic news feed regarding fatalities of local swimmers/fishermen in Papua New Guinea. Though the reported fatalities occurred in 2001, the unusual events drew famous monster fish angler Jeremy Wade to Oceania to investigate and nab one of the possible culprits.

There were apparently two fatalities in 2001 during which the two men had their genitalia bitten off as they pursued their aquatic activities. Both bled to death (these were two seperate occasions) after being bitten by a mysterious, human-like predator in a remote area. As it turns out, the culprit was a large Red-bellied Pacu. Read More »

If you’ve ever had to catch a fish out of your aquarium (or watched the employees at your fish stores catch the fish for you to take home), you can probably appreciate how difficult it can be. These are in relatively small glass or acrylic boxes however; catching a fish from its own home turf is exponentially more difficult! Back when the marine aquarium trade was first gaining popularity in the mid-20^th century, collection was usually laid at the feet of local islanders and fishermen, especially in the small Indo-Pacific island communities that may have had little other source of income. They naturally tried to optimize their collection and profits, but unfortunately this often came at the cost of the animals they were retrieving. Techniques like blast fishing (discussed in a May 2010 blog) and the use of cyanide became common. While not as physically destructive as blast fishing and bombs, cyanide collection was just as deadly. It is now illegal and banned in many areas, but enforcement can be spotty in these isolated areas and some of these irresponsible practices still occur. Read More »

Hello, Frank Indiviglio here.  For centuries, sailors have repeated the legend of the Kraken, an enormous octopus-like creature said to attack ships (please see artist’s recreation).  Today we believe that such tales were based on actual sightings of real-life Giant Squids, which may exceed 60 feet in length (frightening, but never observed attacking ships…as far as we know!).  However, recently uncovered fossil evidence suggests that a giant octopus actually may have haunted the Triassic seas – and that it was able to capture bus-sized marine reptiles known as Ichthyosaurs!

A Fossil-Hunter’s Mystery

Armed with saber-like teeth and reaching more than 45 feet in length, Ichthyosaurs were long thought to have been the Triassic Period’s top marine predators (please see photo of skeleton).  However, recent findings have led some researchers to believe that something, perhaps a giant octopus, was able to make a meal of even these formidable beasts.  Read More »