The Japonica shrimp

Japonica shrimp, originally from Japan, became popular in the hobby thanks to Takashi Amano.

Appearance

These shrimp grow to about 3 to 4 cm. Females grow 1 to 2 cm larger than males, and this difference is clearly visible in fully grown animals. The sex can also be recognized by the pattern on the body: females have a line with longer stripes, while males have a dotted line.

Care

The desired water temperature is around 25°C. Japonicas like a well-planted aquarium - better too many plants than too few - and prefer to live in a group of at least 10 shrimp. The larger the aquarium and the more plants, the larger the group can be. They are also fond of catappa leaves.

Note: Japonica shrimp can easily climb out of an aquarium without a lid, so make sure to have a tight-fitting lid.

With Fish

Smaller shrimp species are often eaten by pufferfish and bettas - keep this in mind when setting up an aquarium. Japonicas are slightly larger and can hold their own among assertive tank mates, although feeding mosquito larvae can sometimes turn into a 'tug-of-war'.

Experiences vary when combining them with larger fish like angelfish - this depends heavily on the tank setup, feeding regularity, and whether the fish have lived with shrimp since they were young.

Why Japonicas are so beloved

Besides keeping the aquarium clean, many people choose this species because they do not reproduce uncontrollably in an aquarium: 10 shrimp remain 10 shrimp (unless one escapes through an open lid).

Reproduction

When a female is ready for fertilization, she emits a scent that excites the males. After fertilization, the female carries her eggs as a grayish 'cloud' under her tail, regularly circulating water through them. Once the eggs are fully developed, she releases her young.

Young Japonicas need brackish water to survive - in a freshwater aquarium, they will only last a day or two at most. For smaller aquarium fish, the tiny young are a welcome treat.

When purchasing, note: the 'mini Japonica' is a different, smaller species that does reproduce normally in a freshwater aquarium.