Highly Underrated Fish: Red-Blue Peru

In today's episode of criminally under-rated Tetras, we present the Red-Blue Peru. Also sometimes called the Bleeding Blue Tetra. These fish, somewhat obviously, originally hail from Deepest Darkest Peru, not unlike Paddington Bear. For many years, they were known to the scientific community only as Hyphessobrycon sp. Red-Blue Peru. They've since been given a distinct species name and now are called Hyphessobrycon margitae, named for Margit Zarske, the wife of Dr. Axel Zarske who was the German Ichthyologist who identified this species for science. He is quoted as saying that “...for many years she has endured and supported my passion for ichthyology.”

Back to being underrated; Red-Blue Tetras are one of those fish that just cannot be photographed. Their colors are muted when they are stressed, and even when they are really colorful, there is a shimmer and iridescence to them that requires you see them in motion. The way the light reflects off their deep and striking black band as they swim through shafts of light literally sparkles shades of blue and purple. This darkly colored band is bordered top and bottom by a thin red bar that is similarly iridescent. It doesn't even show up that well in video. It's somewhat like taking a picture of an amazing, horizon encompassing full moon, only to see the photo turn out with a miniscule white orb.

For long-term readers of our species profiles, you'll know we are all big fans of Tetras, and these are no exception to this generalized adoration. In fact, these are often only available as wild caught specimens, and their remote range and specific habitat makes them somewhat rarer than most of the Tetras you commonly see in your Local Fish Store. The wild caught caveat to these fish means that the water chemistry, and water quality parameters of your tank are of slightly more importance than if you were going to add a group of Neons to your tank (no shade on the Neon Tetras, love those too.) The water should mimic the river system the Red-Blues come from, the Rio Nanay in Peru. This river system features soft, slightly acidic, clean water. Your tank water should have a pH between 6 and 7, and a GH under 10 ideally. They may be tolerant of slightly higher hardness values. Keep the nitrates under 20ppm and the temperature stable, somewhere in the range of 75-80.

Red Blues are excellent aquarium fish, being peaceful and hardy, though they will pick on each other when establishing territories. They'll do well in a variety of displays, especially planted displays that will allow them to feel very secure with all the cover they provide, and a nice, lush background color to make the fish really pop. These are small fish. Most of the specimens you'll see will be between half and three quarters of an inch. They rarely get bigger than an inch and a half. Mature males will show the best colors, which is an almost universal Tetra trait. Color is always dependent on light, background and diet.

Ensuring your fish get the very best nutrition will leave you with the healthiest (and ergo most colorful) aquatic pals. This means feeding them a high quality, varied diet. In the wild, they're omnivores and will chow down just about anything that floats past them. In house, we feed them a mix of Gamma foods that includes Daphnia, the full range of Brine Plus, Cyclops and Tubifex. As wild fish, they are not accustomed to pellet foods, but because of their natural feeding habits, we've found it pretty easy to get them to accept Nutramar Freshwater Complete pellets. Here at Aquatropic, we feed them twice a day and suggest you do the same.

One of the keys to keeping Tetras having enough of them. Schooling behavior is a defense system for them in the wild, and there is a social structure for these groups. If you have too few of them, they won't ever feel safe, and worse, they'll beat each other up as they establish their social hierarchy. You should never keep less than six as an absolute bare bones’ minimum and ten to twelve (or more) would be much better. The best plan is to keep as many as you can in the space you have. You can also mix and match Tetra species to tailor the look of your display any way you like. With this in mind, you should still keep at least that bare bones minimum of six in every species you choose.

A group of 12 will be perfectly happy in a 20-gallon tank (though this won't leave you much capacity for other fish.) Tetras love cover, but in the end, they are open water fish and will always appreciate having some space in the tank. Filtration should be strong and should cycle the entire tank volume at least four times per hour (the 20-gallon tank in question would need an 80 gph filter or more.) There is always a balance between making sure you're maximizing filtration while not overwhelming your fish with current. These are wild fish and aren't going to be accustomed to really bright lighting. If your tank setup features high power illumination, acclimate your fish to this condition slowly.

If your display is big enough to house other fish, you're in luck because Red-Blue Tetras do well in community aquariums. Avoid fish that will eat them (obviously) or overly harass them. Some good choices might be other Tetras, Corydoras, Plecos, Pearl Danios, Gouramis etc. If you're looking for ecological correctness, many of these genera are also found in the Rio Nanay along with some Dwarf Cichlids like Apistogramma cacatuoides and others.

Look, we all know Tetras rule, and the Red-Blues add rarity to that already cool package. They have been spawned in captivity, and there is an opportunity here for someone to ramp up regularly available domestic supply of them. If you're looking for something different in your Tetra collection, or a new breeding challenge, or just want the perfect schooler for your peaceful community tank, think about adding some Red-Blue Peru Tetras from Aquatropic today!