Zebrafish

Scientific Curiosity:

The *Danio rerio* is one of the very few vertebrate fish massively used in human medical research laboratories. It shares 70% of its genome with humans and has the extraordinary ability to regenerate heart muscle tissue and the retina if damaged. There is a patented fluorescent genetically modified version (GloFish) in various neon colors, originally created to detect environmental toxins, the possession and sale of which, however, is strictly prohibited by law in Europe.

An Error in Judgment (Space):

Being very small and hardy, they are often sold for tiny 20 or 30-liter (5-8 gallon) aquariums. This is a very wrong approach. Zebra Danios are the marathon runners of the aquatic world: they swim at crazy speeds all day. Confining them in tight spaces is cruel and makes them neurotic. They need long tanks (minimum 80 cm / 30 inches) to be able to make their swimming dashes horizontally. Furthermore, an airtight lid is essential, or sooner or later they will jump onto the floor.

Cool Water, Not Broth:

Originating from the streams of northeastern India, they enjoy cool, oxygenated waters. The classic tropical aquarium constantly set at 27-28°C (81-82°F) will send their metabolism into overdrive: the fish will age prematurely, become deformed and die in a year instead of living the canonical 3-5 years. They can thrive perfectly in a modern home without a heater (at 20-22°C / 68-72°F).

The School Before Everything:

As gregarious fish, they must strictly be kept in large schools. A number of less than 6 individuals will bring out anomalous behaviors, such as aggressive chasing of other species, stress or apathy.