Caring for Opae Ula

Opae Ula, Halocaridina rubra, are a small, red shrimp native to Hawaii. They live in brackish water volcanic rock pools, known as anchialine pools, which are interconnected by an underground network of tunnels. Opae Ula grow to approximately 0.5" long and can live for over 20 years with minimal care. They are unlike any other aquatic pet currently available on the market!


The most important part of Luau Lagoons is the water. Opae Ula require brackish water, which is a mix of fresh and salt water. Over time your Luau Lagoon's water level will drop due to evaporation. To remedy this, simply add a small amount of DISTILLED water (commonly found in grocery stores) until the water level has returned to normal. Salt does not evaporate so there is no need to add any. Do not remove any water in the process. The shrimp do not require a heater or filter, preferring their water still and stagnant. Whatever temperature is comfortable for you is comfortable for them. Ideally you want to stay between 55°F and 85°F.


Every part of your Luau Lagoon has been carefully researched and selected to provide the optimum environment for your shrimp! Calcium is extremely important to shrimp health and helps them grow their shells. Luau Lagoons are currently only available with aragonite sand made from crushed, fossilized coral. This will slowly add calcium to the water for the shrimp to absorb. The coral rubble option we offer will also provide the needed calcium.

We recommend giving your Luau Lagoon 6-8 hours of light a day. Do NOT place in direct sunlight. Direct sunlight can quickly increase the water temperature as well as grow too much algae. Normal room lighting is sufficient to grow algae, which can sometimes be difficult to see. If you notice an overabundance of algae try reducing the amount of light and restrict feeding until the shrimp have a chance to clean it up.


The majority of an Opae Ula's diet comes from the algae that naturally grows. Over time the shrimp will consume most of the available nutrients. By feeding 1 pellet per 3 shrimp just once a month you can provide those necessary nutrients for proper health. If your Luau Lagoon has a lot of algae you may skip the feedings for up to 6 months. The more you feed, the more algae grows. Too many nutrients can cause an imbalance in the ecosystem and potentially harm the shrimp. When in doubt, feed less.

Here at Aquattics we feed our Opae Ula Omega One Mini Algae pellets. The pellets are the perfect size for adults to pick up and swim with!

When you first receive your Luau Lagoon you'll need to feed 1 pellet per 3 shrimp once a week for 2 months. This will allow the algae to build up a bit. After 2 months you may feed once a month.


Opae Ula typically only breed in tanks 0.5 gallons or larger. Females must molt and shed their exoskeleton to become fertile. Once impregnated, the eggs move down and attach to the underside of the female's abdomen (we call this being berried). The growing eggs are a brownish red and can take a month to hatch. Opae Ula hatch into a larval form we call floaters. The babies resemble tiny commas free floating around the water. They do not eat during this stage. After 15 days the babies will molt and become tiny versions of adults.

Photo of a freshwater shrimp molt courtesy of @nano_naturae on Instagram.


Shrimp need to shed their exoskeleton in a process called molting in order to grow and function correctly. Sometimes you'll find a "ghost" of a shrimp, fear not! This is completely normal and the shrimp will dispose of it in time. 

Closed Ecosystems

Some companies market Opae Ula in tiny sealed systems. These systems typically only survive a few years at most. Not being able to add food means all the nutrients eventually get locked inside the shrimp. Without them they will get a little smaller and more sickly with each molt until they eventually die. Occasionally introducing fresh oxygen also helps to keep the shrimp in top health. Luau Lagoons were created to fix the issues found in closed systems while still being as simple to care for as possible.