Anostomus anostomus and
Anostomus ternetzi
an-oh-STOH-mus an-oh-STOH-mus

A. ternetzi above and A. anostomus below
FromGuianas, Orinoco, Upper Amazon
LengthA. anostomus 7"
A. ternetzi 5-6"
FoodOmnivore, Limnivore
pHslightly acid

Anostomus anostomus and Anostomus ternetzi are two similar appearing species. The fins of A. anostomus have red tinting where those of A. ternetzi are clear. The black central stripe on A. anostomus ends in a black arc at the base of the dorsal fin where on A. ternetzi it ends with a gold arc.
Anostomus anostomus
Anostomus ternetzi

A proper environment should include rock crevices, roots, driftwood or lots of plants for the species to be able to retreat into. I use lots of Swahala driftwood where they are found hiding not so much as loners but in small groups.
They eat flake food, frozen tubifex worms, algae wafers, DoroMin and DoroGreen, fresh spinach and zuchinni, chopped shrimp, canned peas and green beans. They will browse on algae growths and if deprived of vegetable matter may nibble on plants.
a pair of A. ternetzi

Several A. anostomus and A. ternetzi above yet another anostomus species - Anostomus trimaculatus.
Wholesalers have been selling A. anostomus and A. ternetzi indiscriminately as simply Anostomus making it difficult for the local fish store to procure an individual species.

I have seen one fairly mature specimen for sale that was definitely a cross between the two species. It was not an attractive cross and I hope it doesn't happen often.

They both have their attributes, where A. anostomus is perhaps more colorful, A. ternetzi has a slighly better temperment. In a community tank with predominately small fishes A. ternetzi is the better choice. In my own herbivore tanks containing fishes such as Leporinus, Distichodus and Red Hooks the A.anostomus are among the smallest fishes.

An A. anostomus nestled in with a Striped Peacock Spiney Eel

I once had an Anostomus ternetzi form a strange relationship with an ailing Pearl Gourami. The Pearl Gourami had developed a tumorous growth around his pectoral fin that was encumbering his swimming and threatening his death. The Gourami would not only allow the A. ternetzi to nibble on the growth but would pursue him insistently, turning the infected fin toward him until the growth was completely incised.
In Baensch's atlas he makes a discerning remark in regards to Anostomus anostomus. He says "Anyone who has not kept this fish cannot be called a true aquarist".