The lemon tetra (Hyphessobrycon pulchripinnis) is a species of tropical freshwater fish which originates from South America, belonging to the family Characidae.

The eye is a notable feature of this fish, the upper half of the iris being an intense red, in some specimens almost gemstone-ruby in appearance.

Determining the gender of the fish is achieved in adult specimens by examining the black outer border of the anal fin.

The lemon tetra is an Amazon River fish species, first collected from the basin of the Rio Tapajos, near to Santarém, Brazil.

Lemon tetras fare best in a planted aquarium, where they should be kept as schooling fishes, allowing them to replicate their wild behaviour as closely as possible.

Extremes of high pH (8.0 or higher) and hardness should be avoided, as these will subject the Lemon Tetra to potentially life-threatening stress.

The lemon tetra is particularly fond of live bloodworms (these are the aquatic larvae of Chironomus midges) and will attack this particular food item with a relish that has to be witnessed to be fully appreciated!

Displays are principally performed between rival males, which position themselves in a slightly head-up posture, unpaired fins held erect to appear as large and as imposing as possible, and swim forwards with 'flicking' movements of the body.

No damage is incurred by either contestant in these events, and evenly matched males that are at a similar level in the social hierarchy will continue such behaviour for 30 minutes or more at a time.

Tens of thousands of pairs will spawn together, and choose thickets of fine-leaved aquatic plants as the repository for their fertilised eggs.

The courting gesture of the male consists of a quivering motion, with a head-down posture, and the 'flicking' of the unpaired fins in such a manner as to generate flashes of yellow colouration in the visual field of the female.

A breeding aquarium for the lemon tetra thus requires good quality filtration and aeration, fine leaved plants, and an 'egg trap' present to prevent large-scale losses because of the aforementioned parental instincts.

Temperature should be slowly raised over a period of a few days to 28 °C, the pair conditioned with copious quantities of live foods if possible, and the aquarium should be sited so as to receive illumination by morning sunshine, as this is a well-documented spawning stimulus for the lemon tetra.

The fry appear to be almost transparent at first, with the exception of the eyes, and do not begin to develop the 'lozenge' shape of the adult body until the differentiation of the finfold into the unpaired fins is complete (around 4–6 weeks).

When it comes to health and disease concerns Lemon Tetra (Hyphessobrycon pulchripinnis) are relatively hardy but are not immune to common freshwater fish ailments.

They are susceptible to diseases such as Ichthyophthirius multifiliis (Ich), which presents as white spots on the skin and fins, and various fungal infections that may manifest as cotton-like growths.

With proper care and attention to water quality and nutrition, Lemon Tetras can live a healthy life, contributing to the dynamic ecosystem of a home aquarium.