What Do Emerald Crabs Eat? Emerald Crab Eating Habit

People love emerald crabs because they are small and give their aquariums a new look. But most people need to learn what do emerald crabs eat. If you are planning to put some emerald crabs in your aquarium, you have to know their’ eating habits. Otherwise, you may lose some of your precious aquarium fish.

Emerald crabs are one kind of scavenger, meaning they will eat leftover meat or plants. Emerald crabs also love to munch on algae, mainly bubble algae and hair algae. They are also omnivores, which means they eat anything. If you need an in-depth explanation of what emerald crabs eat, check out this blog!

About Emerald Crabs

Emerald crabs (Mithraculus sculptus), also known as green crabs or mithaculus crabs, Their body color ranges from green to sage, making them camouflage with other plants. They can easily hide in the marine bush and camouflage themselves to hide from predators.

They are semi-aggressive and easy to care for, making them perfect for aquariums or reef tanks. Emerald crabs are saltwater crabs, so make sure you are not keeping them in freshwater aquariums.

People keep emerald crabs in their aquariums or reef tanks to eat algae. However, they also eat leftover meat from the aquarium. If there are emerald crabs in the ocean, they will consume any leftover fish that a predator has consumed.

Emerald crabs can reach a maximum size of 1.5 to 2 inches. Since they are so small, any aquarium can accommodate them. To keep emerald crabs, you need a tank with a minimum capacity of 20 gallons.

The aquarium or reef tank’s water flow must be moderate to keep emerald crabs. The pH range of the aquarium should be 8.0-8.4 for emerald crabs. If you are planning to keep a few emerald crabs in an aquarium, keep the temperature between 76 and 82 degrees Fahrenheit.

What Do Emerald Crabs Eat?

Emerald crabs are both omnivores and scavengers, which means they consume both plants and meat. This particular crab spends a good amount of time looking for food scraps and algae. It’s even known to eat bubble algae and hair algae – two types of aquarium algae that most other cleaners stay away from. Plus, these animals will also pick up any trash or edible organisms they come across.

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If you are keeping emerald crabs with other fish, they can feed on the leftovers of your fish’s meals. People may add some sinking pellets or frozen foods as a treat for the emerald crabs. You can also give them some blanched vegetables like spinach and cucumber.

Emerald Crab

You can feed Emerald crabs dried nori, chopped shrimp, or other food supplements if you don’t have enough algae. However, they are nocturnal, so they hide under rocks most of the day and only come out to eat at night. Because of this trait, you’ll have to hand-feed them when it is time for them to consume their meals.

You can easily feed them because they are not picky. Emerald crabs don’t have any special diets. This means keeping emerald crabs in your aquarium is cheap.

What Do Emerald Crabs Eat in A Reef Tank?

You don’t have to worry about feeding the emerald crabs in a reef tank because they will scavenge for algae and food scraps. If you don’t have enough algae in your reef tank, you can feed them dried seaweed.

You can also feed them diet supplements or chopped shrimp in your aquariums. Emerald crabs do love to eat shrimp, and they can fit those tiny pieces into their mouths.

How Do Emerald Crabs Eat?

The emerald crab has two claws that are called pincers. These claws help them to capture food, cut it into pieces, and eat it. They also have four walking legs that can hold the crab while they prepare their meal or scavenge for food.

When emerald crabs eat, they sit on their hind legs and pull pieces of food into their mouths with their pincers. They use their claws to pinch and cut the pieces, then swallow them down.

How Do Emerald Crabs Live?

The Caribbean Sea and the Gulf of Mexico are the main regions where emerald crabs are found. They live in shallow water and eat algae. You will also find emerald crabs in the reef area.

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The most popular crab in the marine aquarium trade is the emerald crab. They almost always hide under rocks or corals to keep themselves safe from predators. However, people still keep them in their reef tanks to get rid of algae and meat scraps.

Also See: How Long Do Emerald Crabs Live? Emerald Crabs’ Life Span

Anatomic Structure of Emerald Crabs

Emerald crabs are crustaceans and part of the Arthropoda phylum. Their flat, shiny, green, finely sculpted carapace is covered in whitish material that adheres to the projections. In addition, the chelae are green, spoon-shaped, and white-tipped. The legs used for walking are hairy, somewhat paler in color, and frequently covered in encrustations.

Emeralds are ten-footed crustaceans, which means they are decapods. They have ten legs, which include two claws.

Here is the anatomic structure of emerald crabs:

The Cephalothorax

The carapace is another name for the body’s hard dorsal and lateral covering of the head and thorax. It shields the crab’s vital organs from the top but not the bottom (brain, heart, stomach, bladder, testicles, or ovary).


A joined head and chest are a defining feature of crabs. Several appendages are found on the head segment (cephalic):

  1. both the first and second antennae (antennule and antenna), and
  2. the mandible, the first and second maxilla, and the first to third maxillipeds.

Furthermore, it has compound eyes which are stalked.

Thoracic (chest)

The first peraeopods are typically referred to as chelipeds because of their enlarged pincers (chelae). The next four pairs of pereiopods primarily use their feet for locomotion and sporadically for foraging.


Crabs can see in all directions thanks to their compound eyes. Compound eyes are very sensitive despite having poor focusing abilities. They benefit from seeing UV light in low light and picking up on even the smallest movements around them.

Antennae and Antennule

Crabs and other crustaceans typically have two pairs of antennae, or “feelers”:

  1. The first antennae are two pairs of short antennules.
  2. Two long antennae (second antennae), one set.

They have much smaller antennae and antennules than crayfish and shrimp. Additionally, in some species, they are so small that we hardly ever see them.

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They orient themselves in hazy environments and gather tactile data using their long antennae. Antennae can easily pick up the vibrations of the water near the crab.


Do Emerald Crabs Need to Be Fed?

Emerald crabs can eat anything, which means they are basically omnivores. However, many people sell emerald crabs as herbivores, which is somewhat incorrect. This means emerald crabs will do anything in your reef tank, such as leftover foods, algae, copepods, etc.

Will Emerald Crabs Eat Corals?

Emerald crabs are omnivores, meaning they will also eat corals. But they do not eat every coral species. Emerald crabs attract coral polyps, a type of coral with small polyps. Emerald crabs can eat these coral polyps.

Can Emerald Crabs Live with Shrimp?

Emerald crabs can live peacefully with shrimp in the same aquarium because they do not prey on them. Shrimp and emerald crabs have a peaceful bond, meaning they do not prey on each other. That means you can put shrimp and emerald crabs in the same aquarium.

Do Emerald Crabs Eat Zoa?

Yes, emerald crabs will eat zoas. They are omnivorous and will feed on anything that’s available in the tank, including zoa polyps. Keep an eye on your emerald crab to make sure it does not eat all of the zoas in your tank. Removing it from the tank may be best if you see your emerald crab is eating your zoas.


Now that you know what emerald crabs eat feeding them will be simple. If you already own emerald crabs, be sure to provide them with a healthy diet plan. Emerald crabs don’t necessarily need a specific diet just because they don’t have one. With the right diet, keeping your emerald crab as healthy as possible is essential.

Emerald crabs are prized in aquariums and reef tanks because they maintain the ecological balance. Emerald crabs are best for the marine ecosystem in addition to reef tanks. Make sure we are not harming them.

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