Court Jester Goby Care Guide

Koumansetta rainfordi

Minimum Tank Size10 Gallons
Water Parameters72-78 F, pH 8-8.4, Salinity 1.020-1.025

The Court Jester Goby is a beautiful fish who provides a lot of flare. As they can be kept in smaller tanks they are a hobby favorite. The goby is reef safe, however they can sprinkle sand on low placed corals. They can also present some challenges when it comes to feeding, so be ready for a bit of extra work should you get a picky eater.

Remember to keep a completely sealed lid. These fish can be quite skittish and are prone to jumping. Their small bodies make even small opening a danger

Behavior & Aggression

While these fish are primarily sand sifters, they are not sitting blennies. Instead these guys stay swimming in the water column at all times, swimming about like a wrasse or chromis. This speaks to their more timid natures, as they frequently dart away if any fish sneaks up on them.

The Court Jester Goby is peaceful towards all fish except for its own kind. While this is true of all fish, the Court Jester Goby is actually fairly easy to breed. Because of this many owners will keep multiple of these gobies in the same tank. To do this you will need a larger tank with plenty of space, hiding spots and sand.

When stocking your tank you will need to treat this goby as a prey fish. They can react slowly at times and are very easy target for more aggressive fish. Even wrasse should be avoided in most cases.

Diet & Feeding

This is what will make or break your gobies lifespan. Some Court Jester Gobies will readily accept frozen and flake foods, either taking them straight from the water column or picking them up as they hit the ground/rocks. This can happen more frequently with captive bred gobies and encouraged further by having low competition when it comes to feeding. Unfortunately most of these gobies will refuse prepared foods, sticking strictly to sifting sand and pecking at rocks.

For picky fish I highly recommend watching their movements and feeding habits. Once you’ve established the Court Jester Gobies frequented feeding spots you can attempt to target feed them. This is done by securing nori(edible seaweed) in the location they frequent. This is much easier with gobies who frequent the rocks. For sand sifters I recommend using smaller rocks to keep the nori in place.

For those looking to go the extra mile the same can be done with mysis & brine shrimp. Simply bury these (not too deep) in their frequently sifted areas. While mine did spit the first piece out he did keep the others that he found. These shrimp must be small, cut pieces. They will not accept whole shrimp.

Keep in mind that many Court Jester Gobies will continue to refuse prepared foods for their entire first year, and sometimes even longer! Because of this I recommend you have a well aged sand bed before adding this fish.

Natural foods would be most forms of algae growing in the tank. The most frequently eaten algae are cyno and soft hair algae. They will not eat tougher hair algae or red hair algae. While this may make the Court Jester Goby an amazing janitor for algae blooms, you will need to ensure you have a more consistent form of food for them.


Like most gobies the Court Jester Goby is impossible to distinguish the gender of. Thankfully they can and will change genders if they are looking to breed and are not kept in too small of an environment. The larger, more dominant goby will become male while the smaller fish will remain female.

Spawning will take place in burrows, making low hanging ridges ideal when attempting to breed these gobies. Once the eggs have been laid the male will protect the cavern from all other fish, including the female. These eggs will hatch within 3 days, sometimes faster depending on your tanks temperature. The warmer the water the faster the hatch will be.

The fry are quite small, only 2mm at most and will feed on their egg sacs for the first few days. After that they will need to feed on microorganisms. This makes rearing them incredibly difficult, with the majority of success being in breeding facilities rather than the home aquarium.

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