Gobies sometimes form symbiotic relationships with other species. Some goby species live in symbiosis with burrowing shrimps. The shrimp maintains a burrow in the sand in which both the shrimp and the goby fish live. The shrimp has poor eyesight compared to the goby, but if it sees or feels the goby suddenly swim into the burrow, it will follow. The goby and shrimp keep in contact with each other, the shrimp using its antennae, and the goby flicking the shrimp with its tail when alarmed. These gobies are thus sometimes known as watchmen or prawn gobies. Each party gains from this relationship: the shrimp gets a warning of approaching danger, and the goby gets a safe home and a place to lay its eggs in.
Corals and Zooanthellae Algae
Although corals can catch small fish and animals such as plankton using stinging cells on their tentacles, these animals obtain most of their nutrients from photosynthetic unicellular algae called zooxanthellae. Consequently, most corals depend on sunlight and grow in clear and shallow water, typically at depths shallower than 60 metres (200 ft). These corals can be major contributors to the physical structure of the coral reefs that develop in tropical waters.
This is why in a reef aquarium with corals, we have to have powerfull lights simulating the Lumens from the sun. This allows the zoanthellae algae to create food for the corals to grow.
ClownFish and Anemone
Clownfish such as the Clown Anemone fish (in my tank) are the only species of fishes that can avoid the potent poison of a sea anemone. There are several theories about how this is accomplished:
The Clown Anemone, hosts only certain type of anemones, the Bubble Tip Anemone is a favorite host for the Clown Anemone fish.
The mucus coating of the fish may be based on sugars rather than proteins. This would mean that anemones fail to recognize the fish as a potential food source and do not fire their nematocysts, or sting organelles.
The coevolution of certain species of clownfish with specific anemone host species and may have acquired an immunity to the nematocysts and toxins of their host anemone.
Blood Red Cleaner Shrimp and Larger Fish
A cleaning station is a location where fish and other marine life congregate to be cleaned.
The cleaning process includes the removal of parasites from the animal's body (both externally and internally), and can be performed by various creatures (including cleaner shrimp and numerous species of cleaner fish, especially wrasses and gobies).
When the fish approaches a cleaning station they will pose in an 'unnatural' way to show the cleaner shrimp that they want to be cleaned and pose no threat, this can be pointing in a strange direction and/or opening the mouth wide. The cleaner shrimp will then eat the parasites directly from the skin of the cleaned fish. It will even swim into the mouth and gills of the fish to be cleaned.
Cleaning stations are often associated with coral features, located either on top of a coral head or in a slot between two outcroppings.
