fish · Serrasalmidae
Redhook silver dollar
Myloplus rubripinnis
Wild range: Much of northern South America: the Amazon and Orinoco basins and the rivers of the northern and eastern Guiana Shield (FishBase; Seriously Fish). (South America)
At a glance: Redhook silver dollar care
Compiled reference information. Review the care notes and original sources below.
What temperature is listed for Redhook silver dollar?
The compiled profile lists 23.0–27.0 °C for Redhook silver dollar (Myloplus rubripinnis). Check the original sources below for context and differing recommendations.
What tank size is listed for Redhook silver dollar?
The profile lists a minimum tank volume of 125.0 US gallons (473.2 liters). Volume alone does not establish suitability; consider dimensions, group size and other inhabitants alongside the full care notes.
What pH is listed for Redhook silver dollar?
The compiled profile lists a pH of 6.0–7.0. Review the cited care sources alongside the other water parameters in this profile.
Natural habitat
A large, disc-shaped serrasalmid (relative of pacus and piranhas) commonly sold alongside true silver dollars. It is told apart by the bright red, black-edged anal fin, which forms a hook-shaped lobe, and it grows much bigger than Metynnis silver dollars: about 25 cm in aquariums. Juveniles are sold at 4–8 cm, so buyers often underestimate the adult size. It is a peaceful, skittish schooling herbivore that eats almost every aquarium plant.
Where they are found
Catalog primary Myloplus rubripinnis (Müller & Troschel, 1844): ITIS TSN 163255 valid (ITIS TSN 163254 Myleus rubripinnis is listed as invalid, accepted name Myloplus rubripinnis), GBIF 2353404 accepted, FishBase and Seriously Fish use Myloplus. The trade still widely sells it as Myleus rubripinnis, so that name is kept in aliases. Other listed synonyms: Myletes rubripinnis (original combination), Aphyocharax rubripinnis, Myletes luna, Myleus rubripinnis luna, Myleus rubripinnis rubripinnis. Family Serrasalmidae, subfamily Myleinae. Not to be confused with Metynnis silver dollars (catalog silver-dollar, M. hypsauchen; also M. argenteus), which stay much smaller and lack the red hooked anal fin. Size: aquarium adults about 22–25 cm (Seriously Fish 25 cm SL; Atlarium 25 cm; AquariumStoreDepot 22 cm), while FishBase records wild fish to 41.5 cm TL and 2.5 kg. IUCN: Least Concern (assessed 21 Dec 2020, via FishBase and GBIF).
Aquarium care
Plan for adults about 25 cm long kept as a group of five or more, so a tank of at least 125 US gal / 475 L with about 180 cm or more of swimming length (AquariumStoreDepot, TankFlare and Underground Aquarium 125 gal for a school; Atlarium suggests 600 L or more; Seriously Fish gives 180 × 38 cm, about 265 L / 69 gal, and Tropical Fish Keeping 75 gal as bare minimums for a small group). Juveniles can be grown on in smaller tanks for a while. Keep it at 23–27°C, pH 6.0–7.0 and soft to moderately hard water, about 4–10 dGH (Seriously Fish; FishBase; Atlarium; Tropical Fish Keeping). It eats almost all live plants, including many hardy species, so use driftwood, rocks and artificial plants. It is a heavy feeder with a high bioload, so use strong filtration and large, regular water changes. It is nervous and can bolt into the glass when startled: keep the lighting dim, avoid switching bright lights on suddenly, give cover along the sides and back, and fit a tight, heavy lid because it jumps (Seriously Fish; Atlarium; AquariumStoreDepot).
Feeding
Mainly herbivorous: in the wild it eats the leaves of submerged and overhanging plants. Make vegetable matter most of the diet: spirulina flakes or pellets, algae wafers, blanched courgette (zucchini), cucumber, peas, spinach and lettuce, plus duckweed or Elodea grown separately as a treat. It also takes most prepared foods and enjoys occasional bloodworm and brine shrimp. Feed two or three times a day in amounts it finishes quickly (Seriously Fish; FishBase; Atlarium; AquariumStoreDepot).
Compatibility
Peaceful schooling fish: keep at least five together, because single fish or pairs stay skittish and hide. Good tankmates are other large, calm fish such as plecos and doradid catfish, larger peaceful cichlids and other silver dollars. It is often used as a dither fish with big South and Central American cichlids. Small fish and shrimp may be eaten, and it will destroy a planted tank. It has strong teeth, so handle large adults with care (Seriously Fish; FishBase; Atlarium; Tropical Fish Keeping).
Breeding
Rarely bred in aquaria because of its size. Males have a longer, two-lobed anal fin and females a straight red hook; mature males may also show more red on the flanks. In the wild, pairs spawn over gravel, with the female ploughing a furrow with her anal fin as eggs are laid, and there is no parental care. Commercial fish come from wild collection or large pond culture. One hobbyist reported raising about 50 fry to adulthood in a 150 US gal tank, but there is no established home breeding method (FishBase; Seriously Fish; Atlarium; Tropical Fish Keeping).
Sources
Compiled from multiple independent care sheets — not copied from a single site.