Taxonomy & naming
Apistogramma sp. "D37" is an undescribed form identified in the hobby by a D number. These numbers come from the German magazine DATZ's catalogue of undescribed Apistogramma, which is why the same fish is also sold under the German name Kiemenfleck, meaning gill spot. A D number is a trade identifier only: it carries no authority, year or type specimen. The form is undescribed, and its identity and range are not documented in the sources behind the atlas.
Morphology
Imperial Tropicals describes adults with light silver bodies and a blue-green sheen, and a zipper-like lateral band, which it says marks the Alacrina group. It says males have pink or purple fins, yellow or gold ventral fins and a yellow or gold face, with some variation by locality. Wet Spot lists an adult size of about 2 in for males and 1.5 in for females. These are the sellers' figures.
Habitat
Not documented in the atlas's sources. Wet Spot gives the range only as South America. Genus-level: Apistogramma live in the Amazon, Orinoco and neighbouring basins, mostly in small blackwater and clearwater streams over sand and leaf litter.
Feeding
Wet Spot says it is carnivorous and takes dried sinking pellets, flakes and frozen foods, with wild fish slower to accept dry food. Genus-level: Apistogramma pick small invertebrates from the sand and leaf litter.
Mating
Not documented for this form. Genus-level: Apistogramma males hold a territory and court several females, each of which keeps her own small cave.
Breeding
Not documented for this form. Genus-level: Apistogramma are cave spawners; the female guards the eggs and fry in a cave, and the male defends the wider territory. Wet Spot says to provide a small cave for spawning.
In the aquarium
Imperial Tropicals says the form is an infrequent import. Wet Spot recommends keeping it as a pair, in at least 15 gallons (about 15 US gal), with a sand bottom, plenty of cover and leaf litter, and describes it as semi-aggressive and shy. Its listed range is pH 4.5-7 and 71-82 °F, with soft, acidic to neutral water best. These are the seller's figures.
Conservation
An undescribed form has no IUCN category, and none is claimed here. Population and range data for it are not documented in the atlas's sources.