Tetra is the common name used by many when they refer to fishes belonging to the family Characidae, or the Characins. This family of fishes is rather large as there are about 1,135 known species spread in 146 genera. Tetras found in two continents: South America and Africa.

The cute, the small, and the dainty

The Tetras are very popular aquarium fishes, with well over 300 species available in the Philippines. The diversity of the Characin family showcases Tetras of different sizes, from the diminutive Yellow Phantom Tetra (Hyphessobrycon roseus), growing to a maximum size of about an inch in length, to the humongous Giant African Tigerfish (Hydrocynus goliath), maxing out at six feet.

But for most Filipinos, a Tetra is a smallfish, about an inch or two in length.

Tetras come in a multitude of colors, such as silver, black, red, green, blue, yellow, orange, and white. They are schooling fishes and are best kept in a school of at least six or more, with their brilliant colors flashing in unison as they swim together. It’s a good thing that Tetras are peaceful fishes and most are compatible with other Tetra species, which means a lot of them can be cared for in one tank.

Tetras are generally kept in a community tank setup. Other peaceful fishes who would not eat them may be considered good tankmates.

Planted tank keepers love caring for these colorful fishes, especially because the planted setup brings out the best colors in these small Characins. Additionally, they will not uproot or eat the plants.

Through the years, we’ve cared for many species of the well-loved small Tetras. I can easily count over 50 species and variants in the country, but my top ten include the following.

1. Cardinal Tetra

2. Neon Tetra

3. Runny Nose Tetra

4. Emperor Tetra

5. Serpae Tetra

6. Black Neon Tetra

7. Black Phantom Tetra

8. Lemon Tetra

9. Glowlight Tetra

10. Penguin Tetra

The big, the bad, and the ugly

Many prefer the small Tetras often housed in small tanks. But on the other side of the spectrum is another group who prefer monster-sized Tetras. And the family Characidae have a few representatives under this group.

Smaller monster tetras

Tetras two feet long may be kept in large tanks at home. Those like Banded Leporinus (Leporinus fasciatus), Banded Distichodus (Distichodus sexfaciatus), Emperor Blue Hook (Myleus schomburgki), Vampire Tetra (Hydrolicus scomberoides), African Pike Characin (Hepsetus odoe), Red Flagtail (Semaprochilodus insignis), and Wolf Fish (Hoplias malabaricus), are some of the smaller monster Tetras kept in the average home aquarium with relative ease.

Medium tetras

The next level Tetras grow bigger and would require huge aquariums. The Black Wolf Fish (Hoplias curupira), Red Pacu (Piaractus brachypomus), and Vittatus African Tigerfish (Hydrocynus vittatus) grow less than a meter in length and can be a handful.

Huge tetras

There are some Tetras that grow even bigger and would require Manila Ocean Park-sized tanks. The Black Pacu (Colossana macropomum), Giant Wolf Fish (Hoplias aimara), Golden Dorado (Salminus maxillosus), Sabertooth Tetra (Hydrolicus armatus), and Goliath African Tigerfish (Hydrocynuys goliath) are huge fishes with attitude.

Medium Tetras

The least popular are the in-between Tetras. These are bigger than the one-to two-inch fishes but definitely less than the monster types.

Surprisingly, I had a difficult time creating a top ten list, because my list won’t make ten – not even five. The more popular choices are the Congo Tetra (Phenacogrammus interruptus), Marbled Headstander (Abranites hypselonotus), Bleeding Heart Tetra (Hyphessobrycon erythrostigma), and the rare Colombian Tetra (Hyphessobrycon colombianus). They are hard to come by and the choices are few.

One day, my supplier showed me a Tetra from Colombia called the Denton Tetra, measuring about 3.5 to 4 inches long.

The fish had a rather drab color, but had an exotic appearance and looked really Amazonian. My mind began to wonder about the potentials of this fish, especially since my friend just built a 300-gallon Amazonian tank and was asking me to look for some Tetras not too small for adult Discus and some Eartheaters. The Tetras needed to be big so these cichlids would not eat them. Certainly, these Denton Tetras where good candidates for his tank.

Trying to learn more about the Denton Terra, I searched the internet but found no useful information. It was as if no one has ever heard of it before. After a few days, my search for the Denton Terra led me to the genus Charax.

The genus Charac currently has 35 recognized species, all found in the Amazon water system. Tetras in this genus are known to have rhomboid body shape, with some species being somewhat translucent.

To my surprise, despite my long experience with fishes, the genus Charax remained remained a mystery to me. In fact, none of the 35 species is familiar to me, except the most popular: the Glass Headstander (C. gibbosus). This is only known to me because of the literature I have read and pictures I have seen. But I have never cared for one nor seen one alive.

C. gibbosus, the most popular in the genus, was my initial guess for the Denton Tetra, but further research led me to another species. After reviewing the materials I gathered, I am convinced that the Denton Tetra is the Charax tectifer.

Charax tectifer?

Charax tectifer was originally described as Anacyrtus tectifer by American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist, Edward Drinker Cope in 1870. After further studies, A. tactifer was later reclassified as C. tectifer by American ichthyologist Theodore Nicholas Gill, thus recognized as the current species.

A Characin belonging to the subfamily Characinae, C. tectifer is found in freshwater and its distribution is in the Upper Amazon River basin in Brazil and Peru.

Describing the denton

C. tectifer is a medium-sized Tetra reaching a length of almost 4 inches (10 centimeters). As mentioned, the body shape is rhomboid. The body color is almost translucent to a shade of grey. Smaller specimens have a bit of vertical striping that disappears as the fish matures.

There are two distinct black blots on the fish. One is located in the front third of the body similar to the black blot seen with some Hyphessobrycon species (clear example is the H. serape). Another black blot is found at the center of the peduncle (tail base). This probably act as a false eye that may confuse the predator to attack the tail and not the head. This gives the C. tectifier a chance to escape when the predator misses a fatal attack. Some faint iridescent greenish blue spots may be observed on the gill plate and along the mid-part of the fish just below the lateral line.

The fish has a tall dorsal fin located at the topmost part of the rhomboid body. It has a forked tail or caudal fin. The anal fin is long and is situated behind the ventral fins and extends just before the tail. The adipose fin is clear which terminates with white and black tip. All the fins, except the adipose fin, are clear in color.

The mouth is situated slightly lower, suggesting these fishes probably prefer food in midwater and not the top. The eyes are round and big, suggesting they probably live in the tannin-rich water of the Amazon.

Being a fish from the Amazon, the C. tectifier prefers acidic to neutral water of pH 5.5 to 7.0, and should benefit in a slightly hard to medium water or GH between 4 to 12. Being medium-sized fishes, they are hardy compared to smaller Tetras prone to sudden death from drastic changes in water parameters. As long as the water parameters are within the above range or slightly off, the C. tectifer should be fine.

This, as well as other Tetras, is a schooling fish and will do best in a group of at least six. A bigger group, of course, is welcome as long as the tank is big enough. Single specimens seem to just cower in an area of the tank and seem to keep still, while those in a school are more daring and would swim in the middle part of the tank.

Best setup

I feel this fish has a lot of potential for the mid-sized Amazon tank. Like previously mentioned, Tetras are mostly small in size and the C. tectifer, along with a few mid-sized ones, would be good addition to bigger tanks while exhibiting the same schooling behavior as other Tetras.

The Amazon is home to over 3,000 species of fishes and the mid-sized fishes are hardly noticed. Given a 75-gallon tank with a nice, adequate filter, one can set up an exotic Amazonian community. Some Echinodorus plants will complete the biotope.

Fish choices are aplenty. Bigger and peaceful bottom dwellers, such as the Hoplo Catfish (Hoplosternum thoracatum), Striped Raphael catfish (Platydoras armatulus), or the Emerald Brochis Catfish (Brochis splendens), or other species of the genus Brochis, are good for beginners; these are like giant Corydoras Catfishes reaching four inches.

Mid-sized Cichlids are plenty in the Amazon. These are quite peaceful and are good for the community setup. The smaller Eartheaters, such as the Red Head Tapajos (Geophagus sp “Tapajos”) and Humphead Eartheater (Gymnogeophagus balzanii), among others, are perfect for this setup. Some peaceful Cichlids, such as the Cupid Cichlid (Guianacara geayi), Bolivian Ram (Mikrogeophagus altispinosus), and similar species are welcome. And of course, everyone’s favorites, the Angelfishes (Pterophyllum species) and Discus (Symphysodon species), are a must.

Some exotic fishes, such as the South American Leaf Fish (Monocirrhuys polyacanthus), Banded Knife Fish (Gynnotus carapo), and others would certainly make this setup very interesting.

For the mid-water schooling fish, a nice big school as the C. tectifer can swim together peacefully as they mingle with other members of the aquarium.

This setup has hardly been done. With the C. tectifer now available, Filipinos can now try mid-sized Amazon biotope tanks that would be the envy of others.

This appeared in Animal Scene magazine’s January-February 2021 issue.

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