There very aggresive but also thers a down side my grandfather put some in his pond 10 yrs or so, first 3 or 4 yrs. it was great caught several over 2 #, then started catching smaller fish, had a biologist check pond he said it was overpopulated, also stated to throw little fish on the bank and let dye because it was hurting the weights. THe bass fishing got better. But it just didn't get fished enough. If I'm not mistaken they spawn like 5 times a yr.