Fish are herded by the noise and sight of trawl doors moving over the seabed and by the sand clouds they create. Hiding is completely natural behavior for most fish, especially when they are first introduced to their new aquarium. If the fish are fighting, it generally means that they are not a compatible fit to be housed in the same aquarium. Many fish are naturally aggressive and will defend their territory to the death. This book covers the different type of activity and behavior of fish also focuses on the fish brain and hormones structure.