Blue Marlin is an important breed that is known for being aggressive. Although Blue Marlin is known for being aggressive, they have the ability to adapt to any situation and handle all conditions, as long as they know what to do and how to do it. The thing about Blue Marlin is that their natural temperament is playful and friendly. The only negative trait that you can see about Blue Marlin is that they are often flighty. This means that when they find that a situation is too exciting for them, they get scared and will often try to flee from it. If your Blue Marlin escapes, he will run right into danger. It is important that you keep the area where he is in safe, as Blue Marlin is not very great swimmers.