Black-ray goby mother bird regurgitating food to her chicks. This way, the shrimp and the goby are kept well fed. Sometimes, if the shrimp is not kept well fed, it will resort to killing the goby. In the wild, most burrows are shared by male and female goby pairs, with their respective shrimp partners, and the female goby will use this burrow as a nesting site to lay her eggs. The obvious benefits to both organisms of this symbiotic relationship make the interaction a form of mutualism. Here is an interesting example of this. The other fish is a dartfish (genus "Ptereleotris").
Monkey goby as amphipods and shrimp. In the Danube lakes Yalpug and Kugurluy, the diet of the monkey goby consists of amphipods, molluscs, and Oligochaeta. In the Khadzhibey Estuary a dozen species of prey make up the diet of monkey goby. Polychaetes, larvae of insects, and shrimp are present in the diet year round. Seasonal dietary additions include crabs such as "Rhithropanopeus harrisii", sea weed such as "Zostera marina", and amphipods such as "Marinogammarus olivii". Certain planktonic crustaceans are also present in the diet of adult gobies. In the northwestern Black Sea, twelve parasite species are known to infect the monkey goby.