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Serpae Tetra – Hyphessobrycon eques


Serpae Tetra

Tetras are amongst the most popular aquarium fishes. There are probably more than 150 distinct species of tetra from which the aquarist may choose and this includes a large number of visually stunning fishes that are bound to enhance any home aquarium.

Is the Serpae Tetra a good community fish? The Serpae Tetra should be considered to be a good community fish and gets on with most species. It is reputed by some to be something of a fin-nipper so avoid keeping it with elaborately-finned species (Guppies, Angel Fish, male Bettas, etc.). 

Key Facts

CategoryKey Facts
Common name(s)Serpae Tetra – also known as:
Blood Characin
Callistus
Callistus Tetra
Jewel Tetra
Red Minor Tetra
Red Serpae
Serpa Tetra
Scientific nameHyphessobrycon eques
FamilyCharacidae
Originate fromAmazon River drainage in Brazil, Peru, Paraguay, Bolivia and northern Argentina in South America
Care requiredEasy to care for and hugely popular
TemperamentPlacid, shoaling fish
Colour & FormOrange to blood-red body with black on dorsal and anal fins. Body relatively deep, top to bottom
LifespanUp to 5 years
Adult sizeUp to 2 inches
DietOmnivorous – eat aquatic insect larvae in nature
Aquarium size24 inches in length or greater
Compatible withMost other Tetras, Barbs, Danios, Guppies and other livebearers, dwarf cichlids, smaller Gouramis, catfish and loaches
Avoid keeping withLong or elaborately-finned species, as the Serpae Tetra can be a fin-nipper
BreedingEasy if you put the fish in the right environment.
Water temp72 – 79 Fahrenheit
Water pH5.0 to 7.5
Water hardness (dGH or dH)1 to 18 dGH

Origins of the Serpae Tetra

Tetras, as a “family” of fishes belonging to the biological family Characidae are found in nature in Africa, Central America and South America.

The Serpae Tetra originates in the Amazon River drainage in Brazil, Peru, Paraguay, Bolivia and northern Argentina in South America. The vast majority of Serpae Tetras available to aquarists are captive-bred. 

Characteristics of the Serpae Tetra

As you can see, the Serpae Tetra is characterized by its almost blood-red body. It will grow to up to 2 inches in the aquarium and live for around five years.  The Serpae Tetra is also known by the following names:

  • Blood Characin
  • Callistus
  • Callistus Tetra
  • Jewel Tetra
  • Red Minor Tetra
  • Red Serpae
  • Serpa Tetra

The Serpae Tetra is a peculiar swimmer in that it swims in short bursts, by default, stopping after a short distance before starting another short burst. This is normal for the Serpae Tetra but, if it needs to escape it is fully capable of so doing.

Since the Serpae Tetra has a reputation for being something of a fin-nipper it is advised to keep this species in a larger shoal of, say, ten or more fish, as it has been observed that this negative tendency is somewhat reduced if a larger shoal is maintained. That said, plenty of vegetation to break up lines of sight and avoiding long-finned or elaborately-finned species in the same aquarium is recommended.

The body of the Serpae Tetra is, unlike the Neon Tetra, for example, quite deep (top to bottom) and varies from a deep orange to a blood-red in colour. The adipose and caudal fins are in keeping with the body colour whilst the pectoral and pelvic fins are a darker shade of the body colour. The anal fin has the same colouring as the pectoral and pelvic fins but is edged in black. The dorsal fin begins with the darker shade of orange or red but is mostly black.

The female has a slightly deeper body than the male and also a rounder body, especially when gravid (carrying eggs). The colouring of the male tends to be fuller and richer than that of the female, especially as spawning approaches.

There is usually a black patch on the flank, behind the gills and in line with the spine. Different variants of the species have differing black marks and some have elongated finnage.

The Serpae Tetra tends to inhabit the middle area of the aquarium (top to bottom). That said, it is a vigorous fish when breeding and will readily traverse the entire aquarium.

The Serpae Tetra is, by nature, a shoaling fish and it is generally recommended to purchase six or more fish, as their nature is to swim together as a shoal and they will tend to thrive much better as a shoal. Serpae Tetras do have a reputation for being fin-nippers so it would be best not putting them together with long-finned species such as Guppies, Angel Fish, male Bettas or other elaborately-finned species. Fin-nipping can also be mitigated by keeping a larger shoal – say ten or more of the species.

Serpae Tetras prefer a shaded tank so consider including floating leaves and/or allowing vegetation to grow so that it floats on the surface of the water to provide shade.

It is generally advised that the minimum tank size for Serpae Tetras should be one of 24 inches in length or more due to the shoaling nature of the species, which will enable a small shoal to move around freely. The tank should be well-planted but with clear areas where the fish can swim freely. The water should have a gentle movement.

Serpae Tetras prefer fairly soft, neutral water with a pH of 5.0 to 7.5, with a temperature range between 72 and 79 degrees Fahrenheit and up to 18 dGH (though some aquarists report up to 25 dGH).

The general rule for Tetras is that by keeping six or more of the same species in an aquarium they will be fully aware of which is male and which is female and they will act accordingly.

Most (but not all) Tetras have an additional fin which identifies them as being Tetras and the Serpae Tetra is no exception. If you look between the dorsal fin and the caudal (tail) fin of the Serpae Tetra you will observe a tiny, additional fin, known as the adipose fin. The purpose of this fin is not fully understood but, if it is present on a freshwater tropical fish then you can be pretty certain that the fish is a Tetra.

Tetra comes from the Greek word “Tetragonopterus” which means square-finned and appears to relate to the four fins on vertical plane of the fish (dorsal, adipose, caudal and anal fins) which span the central line of the fish (when viewed from above or below, front or rear) and are not present as a pair (e.g. the pectoral or pelvic fins).

Serpae Tetra – Video

How do Serpae Tetras breed?

Tetras, in general, will scatter eggs by laying them over fine plants such as Cabomba, Fontanalis or Java Moss.

Serpae Tetras, like most species, are noted to leap above the water surface during breeding and in general, so it is advised that the tank should be covered to mitigate the risk of losing fish.

As the female Serpae Tetra becomes ripe with eggs, the difference between the sexes becomes even more evident. If you plan to attempt to breed Serpae Tetras then it is recommended that you have a breeding tank prepared. Such a tank can be empty but you may wish to include a mesh or grid under which the fertilized eggs will fall and/or a sterilized breeding mop.

That said, Serpae Tetras will breed in a community tank and, if the tank is well planted, it is likely that at least a few fry may survive to reach adulthood.

I have observed Serpae Tetras breeding readily and vigorously in quite neutral water but soft, slightly acidic water is the general recommendation

The female will swim vigorously around the tank when she is ready to spawn and, if you include two males then they will encourage her to lay her eggs by bumping into her. She will lay her slightly adhesive eggs which will immediately be fertilized by the male(s) and will either stick to plants or spawning mop or will fall to the bottom of the tank (preferably through the mesh or trap). Once spawning is complete, remove the adults, as they are likely to consume the eggs, given the chance, and take no further parental responsibility.

Spawning usually takes place in the early morning.

Breeding tank for Serpae Tetras

You should prepare a tank of around 20 gallons in size with mature water. The water should be at a pH of around 6.0 to 6.8, a dGH of 18 and, ideally around 78 degrees Fahrenheit with a low level of light.

You may wish to introduce mosquito larvae or bloodworm as an inducement to reproduction.

The female will swim amongst the plants, laying her eggs whilst the male will swim alongside or behind her and fertilize the eggs as they are laid. Typically, the female can lay as many as 300 eggs during a spawning, which may adhere to plants or will sink to the bottom of the tank.

Once the female has scattered her eggs and the male has fertilized at least some of them then the adults should be removed carefully from the breeding tank because they will have nothing more to do with the eggs but they may simply eat them.

Keep the lights off and the tank dark because Tetra eggs and fry are particularly sensitive to the light.

The eggs will hatch typically in a day or so depending on tank temperature and conditions and the fry will become free-swimming after around three to four days after hatching. Keep the tank unlit for the first week or so then gradually increase the lighting.

The newly hatched fry will firstly feed on their yolk sac but, once free-swimming, can be fed infusoria (particularly rotifers) and will also thrive on egg yolk during the first two to four weeks. It is worth mentioning that immediately after hatching, fry seem quite vigorous but will soon go into a resting state before they become free-swimming so please don’t mistake this initial stage as being free-swimming.

After around four days or so add baby brine shrimp. Once the fry are sufficient in size not to be treated as a snack then they can be introduced into the community tank where they will join the existing shoal. Before moving the adolescent fish into the community tank ensure that you have balanced the water temperatures to mitigate the risk of White Spot or other diseases being triggered.

Should your Serpae Tetras have a special diet for breeding?

Adult Serpae Tetras don’t need any particular inducement to breed. That said, it has been suggested that adding mosquito larva may encourage them, presumably because the addition of a new food may “fool” the fish into thinking that it is breeding time. From my own experience, I would always recommend keeping all of your fish in the best possible condition at all times, as this is good for the wellbeing of your fish.

Mike Wheeler

I started keeping freshwater tropical fish in 1972 and it has been something of a passion ever since. In this website, my aim is to build up an everyman's guide to help the everyday aquarist get the best from this inspiring and entertaining hobby.

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