One of my favorite tanks that I care for is the Academy’s cardinal tetra display. It is across from the freshwater stingray collection in the Amazon Gallery of our rainforest and looks like this:
Cardinal tetras have the scientific name Paracheirodon axelrodi and are native to the upper Orinoco and Negro Rivers of the Amazon. They are a small, peaceful fish that likes to live in large groups, or shoals.
Many people confuse cardinal tetras with their more notorious counter-part, the neon tetra. However, they are two separate species with one very easily observed difference. In the cardinal tetra the red stripe on the lower half of the body extends the full length of the fish from the eye area to the tail. In the neon tetra the red stripe only begins at mid-body, roughly below the dorsal fin, and extends to the tail.
Here is a close-up of some of our cardinals so you can appreciate how colorful they are:
You might think that this fish’s bright, metallic stripes would make it rather obvious to predators. In fact, however, the opposite is true because their colors actually change in response to different lighting and background conditions. Here in our colorless and clear aquarium water their coloration appears shockingly bright. But when viewed through the very dark tannin-stained water they inhabit in the wild, their coloration actually appears quite dark. Furthermore, their metallic stripes reflect light only at a specific angle. When the fish are near the surface, this reflects a bright mirror image onto the underside of the water surface and provides a false target for predators.
In the wild cardinal tetras consume a variety of foods including insects, detritus, eggs, algae, fungus, fruit and fish larvae. Here at the Academy we also offer our cardinals a variety of foods including flake food, brine shrimp, baby brine shrimp, bloodworms, glassworms, and algae wafers.
Our cardinals love to hang out amid the live plants in their exhibit and share their home with a handful of other Amazonian fishes like:
The Amazon puffer Colomesus asellus:
The golden pencilfish Nannostomus beckfordi:
The orange-neon corydoras:
And the dwarf sucker-mouth catfish Otocinclus affinis:
Millions of cardinals are caught from the wild and exported from Brazil every year. Despite this, the fishery is widely considered to be one that is managed very well. The fish are not allowed to be caught during the breeding season or shortly thereafter, and the Amazon/Rio Negro area is so vast that fishermen do not go back to the same site for years, thus allowing the cardinals to replenish. Project Piaba is a fantastic organization which works to help educate collectors/exporters and improve the conditions under which the fish from Brazil are caught, conditioned and shipped to the world. Their rallying cry is, “buy a fish, save a tree!” The assertion behind the slogan is that people with a stable economic livelihood from the fishery don’t engage in more ecologically destructive activities, like deforesting. Learn more about it at www.projectpiaba.org.
The next time you visit us be sure to check out this exhibit! Hopefully you’ll love it as much as I do…