| Scientific Name | Gobiodon atrangulatus |
| Difficulty | Easy |
| Final Tank Size | 10 Gallons |
| Diet | Carnivore |
| Water Parameters | 72-78 F, pH 8-8.4, Salinity 1.020-1.025 |
| Aggression | Peaceful |
| Size | 2" |
The Green Clown Goby is quite hardy and will take to a new aquarium quickly. They are quick to breed when kept in a comfortable environment, live over three years and do not fight with other fish. They may start fights with others of their own species in a small tank but will usually mate if there is enough room for multiple to be happy. The main difficulty when keeping these gobies is feeding them, as they like to stay in one spot and do not usually swim towards the feeding area. They do not frequently swim around the tank, instead hopping about as many gobies do, and will almost always be seen sitting still on rocks or corals.
Is the Green Clown Goby Reef Safe?
These gobies are almost entirely reef safe however they may nip at SPS, Small Polyp Stony, corals. Additionally if multiple are kept they are likely to lay their eggs at the base of a coral. This can lead to brief tissue recession on the coral. As the eggs will hatch within a week the coral will typically regrow into the eggs area after they have hatched. This means a breeding pair of Green Clown Goby will inhibit the growth of some corals.
While all the previous info may make the Green Clown Goby sound like a poor choice for reef tanks, they do have a big positive. Their bodies create a mucus that other fish hate the taste of. This will typically make other fish avoid nipping the goby or any of the corals they are frequently on. In a study by Markus Dirnwober butterfly fish were seen to bite corals by 60 to 98% less often when the corals were inhabited by gobies like the Green Clown Goby. This allows us to keep other risky fish in the tank along side this goby.
The short version is the Green Clown Goby is reef safe but may nip at SPS coral and their eggs may cause a few days of coral tissue recession. They are far too small to harm any shrimp that are not babies or feeder shrimp like brine shrimp. They do not bother clams, scallops, starfish, snails or any other invert.
The Green Clown Goby Diet
The Green Clown Goby can be difficult to feed, not due to its diet but the stationary behavior it has. They will feed on food that stays near their home or slowly passes by. Anything floating at the top of the tank or going by too quickly will be ignored. If the Green Clown Goby is not target fed they will frequently starve in the aquarium.
A good diet for the Green Clown Goby should contain:
- High quality flake and pellet foods
- Dried/frozen brine or mysis shrimp
- Diced shrimp
- Copepods
- Live gut loaded brine shrimp
- Frozen bloodworms
- Zooplankton
A good way to feed the goby is to use tongs or tweezers to hold food near their home. They are not quick to feed on free flowing foods but will strike at foods held nearby. You may have to feed them frozen or live brine shrimp before they will accept other types of food.
Another issue the Green Clown Goby has is the inability to tell how much food they will eat. They feed frequently when in the wild but are typically only able to be fed by hand in the home aquarium. They will strike at food taking however much they can get per bite until they are full. Sometimes this will be a lot and sometimes they will only take one bite or even refuse food. The main way to tell if your goby is eating enough is by their body shape. They will quickly become thinner if not eating enough and will be somewhat fat if they are eating well.
If their home is near the top of the tank you can expect them to get some of the food from a broadcast feeding, however this should not be the only way in which you feed them.
They should be fed at least twice a day, with more feedings if they are not eating enough or as much as they had previously been eating. Try to feed them around the same time each day so that they will accept target feeding more easily. Random feedings may startle them into hiding.
Green Clown Goby Tank Requirements
The Green Clown Goby is not picky about their tank. They are such small fish that they will always find a home in tanks with any amount of rockwork. The more caverns you provide the more hiding places they will have. Additionally the more long corals or tree corals you have the more likely they will be to host a coral and stay in the open.
With these two things in mind you should try to limit the number of hiding spots near the back of the tank. Avoid rocks with large holes that the goby can swim into and instead go for large, flat rocks with corals on top of them. This will keep the goby out in the open while still giving them a home they will enjoy. Filling the tank with porous rocks is a sure fire way to rarely see the goby. You can try to make an artificial home using PVC pipes to keep them in sight, but they may ignore it entirely.
As these gobies are so small they are a high risk for jumping. All holes in the tank must be covered. Even a quarter inch hole could be enough for them to slip through with their slender bodies. Use either mesh netting or filtration media to cover the holes in the tanks lid. These holes will usually be around over flow boxes, power cords, heaters and any wires heading into the tank. Additionally strong filters should have a netting applied to their intake so that the goby does not get sucked into the filter. They swim in quick bursts and should be able to escape a filter if they are stuck against the net but cannot swim out of a tube they have been sucked into.
The Green Clown Goby does like to walk on the substrate occasionally. While they have a protective coat of mucus that should stop scratches from rough substrate it is still beneficially to have softer substrate. Mucus lost to scratches will have to be replaced, taking up calories from the Green Clown Goby. Sand or soft rocks work best where as crushed coral is frequently sharp. Large grain sands can sometimes be rough but this is usually a threat to burrowers and not fish who hop along the substrate.
Green Clown Goby Tankmates
Just about any fish can be kept with the Green Clown Goby. They do not start fights unless they have multiple of their kind in a small tank, under 50 gallons. Likewise larger fish do not usually harass them due to their mucus protection. They can still be eaten or hurt by large aggressive fish but should not be the target of frequent harassment. Some good tankmates would be:
- Other Gobies
- Clownfish
- Blennies
- Cardinalfish
- Jawfish
- Damselfish
- Chromis
- Firefish
- Fairy Wrasse
- Peaceful Anthias
One of the biggest draws to this goby is its tiny size and lack of aggression. They can easily be added to nano tanks without causing issues for any of the other fish and will not put much strain on the filtration system. They do not need a lot of space as they rarely leave their homes and make great tankmates to tiny inverts that other fish would frequently harass or eat.
To keep multiple Green Clown Goby it is best to add them at the same time. This will allow them to find separate homes without feeling like a new goby is intruding on their established space. Nano tanks or aquariums under 50 gallons in size should not house multiple Green Clown Goby or attempt to do so unless they have a second aquarium ready to accept a rejected goby.
Green Clown Goby Gender & Breeding
The gender of these fish cannot be determined by the naked eye however they can change sex at most stages of their life. They do not change coloration or size and will simply assume the needed role for breeding with a partner. The resulting female will always be the smaller of the two as the larger male will be tasked with protecting the eggs after spawning.
In small aquariums the Green Clown Goby will not tolerate another clown goby and will fight with them whenever they see one another. To breed this goby a tank of 100 gallons should be used to ensure they have enough space. They may breed in smaller tanks but are less likely to do so. There should be no fish that can ignore their mucus defenses and few other fish that go into rock caverns or around their hosted coral. If other fish are frequently swimming by their homes or scaring them away from their usual spot then the gobies will not spawn.
Raising the aquariums temperature a few degrees will encourage breeding but should only be done if the two fish have a suitable location to lay their eggs as previously mentioned. A stable feeding schedule and lighting schedule will also encourage breeding. If these three conditions are met then the Green Clown Goby has a high chance of breeding. They will typically lay their eggs on the underside of corals, which can cause tissue recession for the coral.
The gobies will defend their fry from other fish however few if any will survive without being removed from the tank. Removed fry should be kept in an aquarium with the same parameters as their original tank. The fry should be fed rotifers for the first two weeks. After this time they can be fed baby brine shrimp along side the rotifers, with less rotifers being added as the fry age. Rotifers should no longer be fed after 25 days from being hatched. After 40 days you can attempt to feed them dried foods or frozen brine shrimp. Around this time the fry should begin to develop their pigmentation or coloration. They can then be moved to an empty aquarium or raised further.
It is important to perform two 50% water changes a week while raising the fry. Use a sieve to prevent the fry from being drained out of the aquarium and do not have the water draining so quickly that fry become stuck against the sieve and die.
For a more in depth breeding information you can read the Gobioid Research Institutes breeding program.
