hi kieran
i will look out for that book thanks, i know that i could only have 2 gobies together in my old tank as it was smaller
but as this is alot bigger i was wondering if i could have one more .
i know they are terrotorial as my watchman is funny to watch as he opens his mouth to chase off the other goby quite funny to watch.....
here is a picture of each goby

this is merric

this is duncan