Thai Micro Crab: New Breeding Progress

20 Mar, 2014

The Thai Micro Crab, or Spider Crab, is a diminutive crustacean with a carapace size roughly the diameter of a pencil eraser. Plant and shrimp safe, they have been gaining quick popularity in recent years. Despite their relatively frequent availability within the hobby, almost no breeding reports have been published.

Microcrabs (Limnopilos naiyanetri) busy filtering for food.

Microcrabs (Limnopilos naiyanetri) busy filtering for food.

Limnopilos naiyanetri (Chuang & Ng, 1991) are a Hymenosomatid crab found in Southeast Asia. The species is characterised by its flat, pilose (hairy) carapace and chelipeds (legs). A popular and enchanting addition to a small invertebrate tank, they are completely peaceful and tolerant of a wide range of parameters and add an additional level of interest to a small tank.

While a shy and unassuming addition, once the crabs settle into a tank, they can usually be found clinging to decor or on the roots of plants, as shown in the video below.

While it has long been said that they complete their life cycle in freshwater, there have not been documented breeding reports with photographs to support suggested success. There is much anecdotal evidence available on the internet, and many reports of the female holding eggs, which change from orange to tan to grey, under her pleon until they hatch into larvae and are released. Some anecdotal breeding information suggests that the larvae may need an orienting light. Many people, myself included, have been working with various strategies to rear them with little success.

In the past, I have seen females release larvae many times, and have seen rare instances of baby crabs in the tank, but have not had any success with any consistent rearing of young. I have had a female holding eggs for several weeks. Without my notice, they hatched into larvae and she continued to hold them. It appears that they have transitioned into young crabs, a very exciting discovery! This suggests that the larval release may be premature, and would explain a lot of my previous failures.

Female microcrab seemingly holding young crabs.

Female microcrab seemingly holding young crabs.

I have them set up in a tank with leaf litter, driftwood, and some low light plants including red root floater, anubias and some bolbitis fern. They spend most of their time in the dense roots of the plants, or the crevices of the wood. They appear to use their pilose (hairs) to detect food, largely eating particulate foods (I use Golden Pearls, and Nano Bites, as well as occasional frozen cyclops).

The tank temperature is around 74F, with a pH of 7.4, gh 7, kh 8, tds around 180. Water changes are done twice a week, consisting of a 25% exchange. Hopefully the baby crabs will be released soon and I will have further success in order to have a better idea of what exactly was the difference with this setup over previous attempts.

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About the author

Rachel O'Leary
Rachel O'Leary

Rachel O'Leary is the owner and operator of msjinkzd.com, a business specializing in freshwater nano fish and dwarf invertebrates. She is a published contributor to such magazines as Amazonas, as well as a renowned national and international speaker. Rachel is a frequent, and colorful, presence at many clubs and conventions in the United States and Canada.

8 Comments

  1. March 30, 2014

    What are the water parameters that you keep them in?

  2. April 02, 2014

    They are kept in my well water, which has a pH of about 7.4, gh 6, kh 7, tds which varies from 150-180. Their tank is unheated, at about 72 degrees this time of year.

    • September 29, 2015

      Have you figured out exactly what got the crabs to survive past the zoa stage?

  3. July 23, 2015

    Where the young successfully raised to adulthood?

  4. July 26, 2015

    I’m looking foward to doing nano aquarium sized animal breeding soon. Sadly I’ll probably not be able to start for a year, but while reading alot about thai micro crabs, I think I know something fail safe for breeding, I can’t wait to try it out, would you be willing to donate some adults?

  5. January 20, 2016

    So I purchased one and poor it in a separate breeder tank with my daughters guppies. A couple of days later my tank was filled with babies. At first I thought it was an infestation of some sort. It had been almost a month and they appear to have grown a tiny bit. I don’t know how I have kept them alive this long but they are still doing great. The guppies don’t bother them and they don’t bother the fish.

  6. March 16, 2016

    Linda are the babies growing or did they die?

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