Page 96 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

94 FRESHWATER FISH DIRECTORY

Metynnis argenteus
Silver Dollar

ORIGINS South America, occurring in the Amazon region
east of the Rio Negro and into Guyana.
SIZE 5 in (14 cm).
DIET Vegetable flakes, pellets, and fresh foods.
WATER Temperature 73–81°F (23–27°C); soft
(50–100 mg/l) and acidic to neutral (pH 5.0–7.0).
TEMPERAMENT Peaceful, shoaling fish.
Shaped rather like a coin, with a silvery body
color, the Silver Dollar makes an impressive tank
occupant, especially when a shoal of these fish are
housed together. They can be sexed quite easily,
since the anal fin is longer in males and has a
reddish tinge at the front. These fish sometimes
display small dark spots on the sides of their bodies,
which may look like a sign of disease but are
actually quite normal. An aquarium for Silver
Dollars needs to be relatively large, with open areas
for swimming and caves for the fish to use
as retreats. Like other large vegetarian characoids,
Silver Dollars are likely to damage the plants in
their tank. It is advisable to include plastic plants
to augment living specimens, which will be at
risk. Living Java moss (Vesicularia dubyana) is useful,
however, because it is attractive yet will not be
eaten by most fish. It will also provide fish with
potential spawning sites.

Mylossoma duriventre Hemiodus gracilis Colossoma macropomum
Hard-Bellied Silver Dollar Slender Hemiodus Black-Fin Pacu

ORIGINS South America, with a distribution from the ORIGINS South America, occurring in the Amazon region ORIGINS South America, widely distributed throughout
southern Amazon basin down as far as Argentina. and into Guyana. most of the Amazon region.
SIZE 9 in (23 cm). SIZE 6 in (15 cm). SIZE 16 in (40 cm).
DIET Vegetable-based foods of all types. DIET Vegetable foods plus small invertebrates. DIET Vegetarian diets and fresh foods.
WATER Temperature 72–81°F (22–27°C); soft WATER Temperature 73–81°F (23–27°C); soft WATER Temperature 73–81°F (23–27°C); soft
(50–100 mg/l) and acidic to neutral (pH 5.0–7.0). (50–100 mg/l) and acidic to neutral (pH 6.5–7.0). (50–100 mg/l) and acidic (pH 6.5).
TEMPERAMENT Peaceful and social. TEMPERAMENT Peaceful and social. TEMPERAMENT Peaceful, even when larger.
The Slender Hemiodus has a thin, silvery body
Adipose with a black stripe in the midline behind the
fin Striped dorsal fin. This stripe curves down the lower
eye
lobe of the caudal fin, where the area beneath it is
red. This characoid needs well-oxygenated water,
and the addition of peat to the filtration system is
recommended, especially at first. Silver Hemiodus
will eat algae as well as plants in their aquarium.

The dark edging to the fins, especially the caudal
The silvery body color may fin, helps to identify the Black-Fin Pacu. The
vary in its depth, but the red edging to the caudal body is a metallic silver, sometimes with a pattern
fin is a consistent feature of this characoid. The of darker spots, and there is a variable orange-red
description “hard-bellied” refers to the narrow, area around the throat. These sizable fish need a
serrated area on the underside of the body between large aquarium, which should be provided from
the pelvic fins and the anal fin. The care needs of the start because the young grow rapidly. Retreats
this fish match those of the Silver Dollar itself. can be provided by rockwork or bogwood.

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