The vampire tetra is an uncommon fish to see in your local fish store, but chances are larger LFS (Local fish stores) will get them in at times. If you tried to do some research on the vampire tetra you will not get very accurate information. Four different species of fish are all put under the same name.
The first vampire tetra, and perhaps the most common is the hydrolycus scomberoides (scomb). The hydrolycus scomberoides you will notice likes to sit at a weird angle with it’s head down and the back of the fish will be up, sort of like a headstander. The scomb also has a dull grey sort of color. The tail on the scomb tends to be brown or black and it fades to clear towards the back. Scombs are notorious for short lives. The largest scomb in captivity is a little over a foot at the Shedd Aquarium. There are no reports of a scomb living for more than two years in an aquarium, arguments include anything from bad feeding habits (living off of goldfish and rosy reds), to a different style of care needed at a foot, to just being a short lived fish. Even in the wild, scombs are not caught bigger than a foot. Hydrolycus scomberoides may very well be one of the tamest vampire tetras with tank mates. The scomb sells for about 20 to rarely 50 dollars online and at local fish stores, usually on the cheaper side though.
The next vampire tetra, almost as common as the scomb is the rhaphiodon vulpinus (raph). Raphs, are more common in the wild but less common at fish stores. Raphiodon Vulpinus is probably one of the most distinguishable vampire tetras. Raphs are much more thin than Hydrolycus species vampire tetras and they have a much longer body. Their body color is a much more metallic silver than hydrolycus scomberoides. When catching food, raphs also move very dramatically sometimes resulting in a backflip after they catch their prey. In the wild and in captivity raphs tend to grow to about 18″. Males will grow to about 15″ when some females will grow as large as 20″, but usually top out at 18″. Raphs are also pretty calm fish, but occasionally they will become aggressive. Normally they are not quite as peaceful as scombs.
The third vampire tetra, and the most rare is the hydrolycus tatauia (tat). Tats are identified by their red/orange fins and large black eyes. Tats tend to be the most home aqaurium friendly only requiring a tank as wide as two feet when full grown and growing to only a foot. Also, hydrolycus tatauia is much more long lived than the hydrolycus scomberoides. It is also said, that tats are much more friendly to tank mates than any of the other vampire tetra species. The only down side to the tatauia is the lack of availability and possible high price. Many LFS very rarely get the hydrolycus tatauia and due to the higher demand can charge a very hefty price if necessary. If you can find a tat, it is not something that should be passed up.
The fourth vampire tetra, and possibly the most popular is the hydrolycus armatus. The hydrolycus armatus is the most aggressive vampire tetra occasionally attacking it’s tank mates. It can be identified by swimming at nearly a level angle, larger fangs and wider body. These are the “payara” you see in the fishing photos online. They will grow to a massive size if given the right room and diet. In aquariums, they tend to grow to about two feet. Armatus are very rarely available at LFS and you will usually have to find somebody selling theirs online and buy it from them. They can sell for anywhere between one hundred and one thousand dollars making them very expensive.
Many vampire tetras need small schools, usually of around six and benifet from South American whitewater conditions (powerheads, well oxygenated water and temperatures in the low 80’s). Scombs and raphs tend to be the most skittish and claustrophobic requiring very large tanks and at least three times their length turning room. If enough room isn’t provided they tend to try to jump out of the tank or swim into the glass frantically. It is also important to know, unless you have a hydrolycus armatus that vampire tetras are not as aggressive as they long and they should only be housed with peaceful or semi-aggressive fish that are large enough not to be eaten in one bite.