Diamond Tetra (Moenkhausia pittieri)
The diamond tetra is a small freshwater fish found near Lake Valencia in Venezuela. In the aquarium trade, it is popular for its very iridescent scales, which catch and reflect light like crystals. Like many other tetra species, this fish is best kept in a small group.
Elma via Flickr

Diamond Tetra (Moenkhausia pittieri)

The diamond tetra is a small freshwater fish found near Lake Valencia in Venezuela. In the aquarium trade, it is popular for its very iridescent scales, which catch and reflect light like crystals. Like many other tetra species, this fish is best kept in a small group.


Elma via Flickr

Rummy Nose Tetra (Hemigrammus sp.)
The rummy nose tetra is the name given to three very similar looking freshwater fish native the Amazon Basin. It’s common name comes from the red blush across its face. In the wild, the fish inhabits very soft, acidic water. In an aquarium setting, breeding in hard water leads to sterility in the offspring.
Mukyo via Flickr

Rummy Nose Tetra (Hemigrammus sp.)

The rummy nose tetra is the name given to three very similar looking freshwater fish native the Amazon Basin. It’s common name comes from the red blush across its face. In the wild, the fish inhabits very soft, acidic water. In an aquarium setting, breeding in hard water leads to sterility in the offspring.

Mukyo via Flickr

Cardinal Tetra (Paracheirodon axelrodi)

Cardinal tetras, and their relatives the neon tetra, are a species of freshwater schooling fish native to South America. Their iridescent blue stripe is thought to work as a defense mechanism to avoid being eaten. The reflective stripe may disorientate predators, especially when many fish are swimming together, making it harder to pick out a single fish.

vii_genau on Flickr, Joachim S Muller on Flickr

Genetically Modified GloFish®
GloFish® is a trademarked brand of genetically modified zebra danios, black widow tetras and tiger barbs, which artificially express various fluorescent genes from jellyfish, corals and anemones. Their colouration is a result of genetic modification, and not from dyes.
Genes are basically sequences of DNA that code for proteins (or polypeptides to be more exact). Genetic codes can be expressed by any organism, as long as they have the gene.
For example, the Green Fluorescent Protein (GFP) gene from jellyfish can be inserted into the DNA of the zebra danio. The genetically modified zebra danio now has the genetic sequence of GFP and will produce it, resulting in its neon glow.
The fish are reported to have reduced fertility, although some individuals are able to breed. The fluorescence gene can be passed from generation to generation, although intentional breeding to sell the fish is illegal as they are patented. The fish are bred and distributed by the company YorkTown Technologies.
GloFish® do not pose more environmental threat than their non-fluorescent counterparts. If released into the environment, they are unlikely to survive if the temperature is too low, or from predation. Their unnatural colourations and reduced fertility do not benefit their survival.
Notwithstanding, the intentional or accidental release of aquarium fish has ravaged some ecosystems.
Info: glofish.com; Image: M Bolt 2012, via Flickr

Genetically Modified GloFish®

GloFish® is a trademarked brand of genetically modified zebra danios, black widow tetras and tiger barbs, which artificially express various fluorescent genes from jellyfish, corals and anemones. Their colouration is a result of genetic modification, and not from dyes.

Genes are basically sequences of DNA that code for proteins (or polypeptides to be more exact). Genetic codes can be expressed by any organism, as long as they have the gene.

For example, the Green Fluorescent Protein (GFP) gene from jellyfish can be inserted into the DNA of the zebra danio. The genetically modified zebra danio now has the genetic sequence of GFP and will produce it, resulting in its neon glow.

The fish are reported to have reduced fertility, although some individuals are able to breed. The fluorescence gene can be passed from generation to generation, although intentional breeding to sell the fish is illegal as they are patented. The fish are bred and distributed by the company YorkTown Technologies.

GloFish® do not pose more environmental threat than their non-fluorescent counterparts. If released into the environment, they are unlikely to survive if the temperature is too low, or from predation. Their unnatural colourations and reduced fertility do not benefit their survival.

Notwithstanding, the intentional or accidental release of aquarium fish has ravaged some ecosystems.

Info: glofish.com; Image: M Bolt 2012, via Flickr

Mexican Tetra or Blind Cavefish (Astyanax mexicanus)

Astyanax mexicanus is a freshwater fish native to Southern Texas and Mexico. As a result of geographical separation and physical differences in their environments, some populations of the Mexican tetra have lose their eyes and colouration.

In the karsts of Mexico, 29 populations of Mexican tetras live in completely dark caves. These populations are known as Blind cave fish and are morphologically different from their above ground cousins.

Blind cave fish are eyeless, relying on their highly sensitive lateral line to detect pressure differences to navigate their physical surroundings. Additionally, they lack any colouration.

This loss of eyes and colour is referred to as a regressive evolution, as the Mexican tetras which originally colonised the caves possessed both eyes and colour. Over time, the pitch black environment gave no benefit for vision and colouration, so those traits were lost over many generations.

Images: H. Zell, © President and Fellows of Harvard College

Diamond Tetra (Moenkhausia pittieri)
Diamond tetras are named for their extremely shiny scales, which are reminiscent of crystals.
úlfhams_víkingur on Flickr

Diamond Tetra (Moenkhausia pittieri)

Diamond tetras are named for their extremely shiny scales, which are reminiscent of crystals.

úlfhams_víkingur on Flickr

Rummy-nose Tetra (Hemigrammus rhodostomus)
Rummy-nose tetras get their name from the red blush across its face, similar to a person who has drunk too much rum. They are native to acidic blackwater rivers of South America. Rummy-nose tetras are a popular aquarium fish, tolerating a wide range of water conditions.
mukyo on Flickr

Rummy-nose Tetra (Hemigrammus rhodostomus)

Rummy-nose tetras get their name from the red blush across its face, similar to a person who has drunk too much rum. They are native to acidic blackwater rivers of South America. Rummy-nose tetras are a popular aquarium fish, tolerating a wide range of water conditions.

mukyo on Flickr