We would like to offer a few comments and suggestions regarding the addition of aggressive specimen(s) to your existing tank.
When Tangs are housed in the same aquarium they can become territorial and aggressive if they are not introduced at the same time. Aggression can vary from individual to individual within each species, so there is no guarantee that even if they are introduced at the same time they will be compatible later on. If hobbyists choose to not introduce the fish simultaneously, then starting with smaller, less aggressive species and gradually working your way up to the larger more aggressive species is the best plan of action.
The easiest way to try and house multiple tangs in larger aquaria is to select fish of different genus. Tangs are most aggressive towards their own species or even their own genus. If maintained in a large enough aquarium and an adequate amount of food is provided, some aquarists have been known to house schools of the same species of tangs together in aquariums that are at least 6 feet in length or more.
It should be noted that mixing tangs of the same genus is the most risky and problematic. For example if one were to try and maintain a Scopas tang and yellow tang (both Zebrasoma spp.) in the same aquarium this will often lead to severe aggression that is detrimental to the health of the fish. In general, fish of the genus Acanthurus and Zebrasoma are normally the most territorial and aggressive fish towards other tangs.
If two conspecifics are collected from different populations and are placed in the same aquarium, aggressive behavior will most likely occur until a new pecking order is established. Unfortunately, the weaker or less aggressive fish often dies, either gradually as a result of stress or quickly from physical trauma inflicted by the stronger fish.
One way to help alleviate this is to section off a small portion of the aquarium with egg crate or some other tank divider, and confine the larger or more established fish in this small area for a few weeks until the new addition can adjust to the new surroundings. Rearranging the rockwork and aquascape in the aquarium will also help. The reason for moving the rockwork around is to help change the established territories of the existing fish, and take the focus off of the new addition.
These methods may not always work and is always best to carefully plan your compatibility beforehand. Proper planning of all the inhabitants we house in our aquariums is a must for the well being of the marine life we maintain. A well established, large aquarium is a must when maintaining tangs, as these fish are often prone to contracting saltwater Ich when stresses, or when housed in newly established aquariums.
We hope you find this information beneficial!
Jessica H.
Technical Support
Drs. Foster & Smith
