CHARACINS




SERRASALMINAE SUB-FAMILY
Colossoma, Metynnis, Myleus, Mylossoma, Serrasalmus are the most commonly seen genera of the Serrasalminae or Piranha sub-family.  This sub-family is infamous some species (genus Serrasalmus ) "man-eating nature."  This reputation is highly exaggerated, although four species have been reported to be dangerous to man.  For this reputation, many states have outlawed the import of some Serrasalmus species.  Nevertheless, all fish in this family should be handled with care as many possess razor-shape teeth.
Piranhas and allies are distributed throughout tropical South America, and reside in virtually every stream, river, or lake in this region. The fish of this sub-family are generally large and inhospitable towards small fish and live plants. Most species will readily devour live feeders and chopped meat, along with plant or vegetable based foods.  
 
Black-finned Pacu
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Colossoma macropomum
SYN : Colossomanigripinnis , C. oculus , Myletes nigripinnis , M. oculus , Piaractus nigripinnis
PD : A tall, laterally compressed fish. It has large eyes and a slightly arched back. The base body color is dark gray to black with spots and marks in its midsection. The pectoral fins are small and blacklike the rest of the fins.
SIZE : Exceeds 28" (71 cm)
SS : Silver-scaled Piranha ( Serrasalmus gibbus ), Black-tailed Piranha ( S. striolatus )
S: bottom, middle
HAB : South America; throughout the Amazon River Basin, in rivers with heavy vegetation.
TANK : 48" (122 cm) or 55-plus gallons (170+ l) is adequate for young fish, up to 6"(15 cm) in length. Fish exceeding 12" (30 cm) require a tank measuring at least 72" (183 cm) or exceeding135  gallons(512 L). Fish larger than 20" (51 cm) are best kept in a  96" (244 cm) tank which has a volume exceeding 200 gallons (756 L). This fish requires a tank set-up much like that recommended for P. brachypomus .
WATER : pH 5-7.8 (6.8), 6-20 dH (10), 73-82°F (23-28°C)
SB : As for P.brachypomus .
SC : See P.brachypomus.
FOOD : An herbivore-plants; vegetables; lettuce, peas, spinach; fruits; oatmeal; pellets; chopped meat; live; fish, worms, crustaceans, aquatic insects. 
SEX: Dorsal fin has sharper extension in male.
B : Not feasible in aquaria.
BP : 10. Breeding has not been accomplished, most likely because of this fish's size.
R : Can be caught using citrus fruit as bait.
DC : 6. This hardy fish is difficult to care for because of the enormous size that it can reach.
 
Silver Dollar
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Metynnis argenteus
SYN : Metynnisanisurus, M. dungerni, M. eigenmanni, M. heinrothi, Myletes argenteus
PD : A tall, laterally compressed fish that is shaped like a disk or plate. It has small eyes and a back. The base body color is silver and the fins are transparent. The belly is slightly reddish silver. A line extends through the iris. The pectoral fins are red. A string of spots extends across the body.
SIZE : To 8" (20 cm)
SS : Other Metynnis species, and fish of the genera Myletes , Mylossoma , and Serrasalmus .
HAB : South America; shallow areas of rivers with heavy vegetation in Guyana
S: middle
TANK : 48" (122 cm) or 55 gallons (210 L) is adequate for smaller fish.  Adult fish should be moved to a tank measuring at least 56" (142 cm) with a capacity of at least 75 gallons (285 L).  The tank should be large and roomy with lots of open swimming areas.  Provide hiding places with solid rock structures and driftwood. The lighting should be dimmed and use a dark gravel bottom.  Live plants will usually be consumed, so use plastic plants as an alternative. Some robust, sturdy plants may not be bothered if the fish are fed insufficiently. Silver Dollars prefer shallow tanks.
WATER : pH 6-7.5 (6.8), 4-18 dH (12), 75-82°F (24-28°C)
SB : Keep with fish of relative size, as smaller fish may be eaten.  The Silver Dollar does best when keptin a school of six or more fish. 
SC : Other "Silver Dollars" (see "Remarks"), Loricarids, Pimelodids, South and Central American cichlids, Pacus, Arawana, Anostomus.
FOOD : Pellets; vegetables; lettuce, peas, spinach; plants; large vegetable flakes; live foods are usually accepted.
SEX: Male has a longer anal fin and has a red marking and front of belly.
B : Only possible in a large, shallow tank.  Silver Dollars often spawn in schools. Recommend water with the following values: a pH 6.0-6.5, a water hardness of 4-8 dH, and a water temperature of 79-82°F (27-28°C). Have floating plants and slightly dimmed light. About 2000 eggs are produced by each female. The eggs fall to the bottom. Remove the adult fish after the spawning.  The fry hatch in 3 days, and are free swimming after 6-9 days. They first eat plankton, but later, will take vegetable flakes.
BP : 9. Breeding is difficult because of the volume of water needed for a group of fish to spawn.
R : Over 20 species of Metynnis are available, with most species reaching about 8" (20 cm) in size. "Silver Dollars" sometimes include other genera including Mylossoma and Myleus .  These genera are difficult to distinguish, although differences are usually apparent in the adipose fin.  Metynnis have a long-based adipose fin, while Mylossoma and Myleus have a short-based, rounded adipose.  An important food fish in South America.  
DC : 5. The Silver Dollar is a hardy fish that, because of its size, must be kept in a large tank.
 
Red Pacu, Red-bellied Pacu
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Piaractus brachypomum
SYN : Colossomabidens, C. brachypomum, C. mitrei, Myletes bidens, M. brachypomus, M. edulis, Reganina bidens
PD : A tall, laterally compressed fish that is shaped like a disk or plate.  It has small eyes and a slightly arched back. The base body color is gray and belly is red. The pectoral and pelvic fins are also red, as is the front part of the anal fin.  The rear edge of the caudal fin is black.  The adipose fin is composed of only one ray. The body is spotted irregularly with gray to black spots. 
SIZE : To 36" (90 cm), usually not more than 18" in aquaria
SS : Red-Bellied Piranha ( Serrasalmus nattereri ), Black-eared Piranha ( S. notatus ).
HAB : South America; Upper Amazon Basin
S: bottom, middle
WATER : pH 4.8-7.5 (6.0), 1-20 dH (8), 72-82°F (22-28°C)
TANK : 48" (122 cm) or 55 gallons (209 l) is sufficient for small fish, under 8"(20 cm). As a fish grows, it must be moved to a larger tank.  Eventually, a  80" (203 cm) tank with 200 gallon (756L) capacity should be adequate for a full-grown, adult fish.  The tank should have large, open swimming areas.  No live plants should be used as they will be eaten. A powerful filter that creates a strong current and filters large amounts of waste should be used. Provide hiding places with large branches of wood and rocks.
SB : A peaceful fish despite its large size.  This large fish can be kept with other large fish.  It is not recommended to combine this fish with small fish, because they may be eaten despitethis fish's herbivorous nature.
SC : Silver Dollars, Piranhas, Anostomus, Central and South America cichlids, Arawana, Pimelodids, Loricarids.
FOOD : An herbivore-plants; vegetables; lettuce, peas, spinach; fruits; oatmeal; pellets; chopped meat; live; fish, worms, crustaceans, aquatic insects.  Young fish will also eat vegetable flake food.
SEX: Dorsal fin has sharper extension in male fish.
B : Unsuccessful in aquaria.
BP : 10. Breeding has not been accomplished in aquaria, most likely because of this fish's size.  This species has been bred in Florida fish farms.
R : Long lived, up to 15 years. This fish is caught-using fruit as bait-and eaten in South America.
DC : 6. This hardy fish is difficult to care for because of the enormous size that it can reach.