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I recently had a terrible experience with a fish that is notoriously considered peaceful (not even semi- aggressive). The fish was "bossy" during feeding but generally peaceful with tank inhabitants that were in place before the fish was stocked, though over time, less bossy (consistent with its peaceful reputation). But when a new addition was stocked (a different species also considered peaceful), the supposedly peaceful fish attacked the new addition and did so repeatedly, including grabbing the new addition by the head (more than once). This began the moment the new addition was placed "in" the tank in the temperature acclimation bag, where the peaceful fish charged the new addition, running itself into the bag where the new addition was lying in the bag.
Over the course of 2 days or so, it became clear the peaceful fish was extremely aggressive with the new addition, and that this behavior wasn't going to change; rather, one had to assume it was going to kill the new addition. (My LFS advised to remove the instigator from the tank.)
Either the peaceful fish was an unusually ill tempered specimen, or it had some distinct issue with the new fish that didn't seem to have anything to do with any factor you might name (territory, order of addition, size/maturity, coloration, etc.). Certainly it did not seem to have anything to do with any factor I could discern. The peaceful fish was just highly aggressive, at least with the new addition, and not with the other inhabitants.
I have read many postings, but I wanted to ask directly and see if anyone shares information that might be more clarifying.
How useful should we consider the aggression ratings commonly assigned to fish?
Part of the reason I ask is that I have wanted to stock a "semi aggressive" fish, because I like the fish. But I'm concerned about such a fish in my present tank. If these ratings aren't worth much, I'm inclined to add the fish (last fish to be stocked), in part since many relate good experiences with this fish, considering its reputation unjustified.
I am deliberately leaving out any mention of the species I have experience with or have in mind, because I'm interested in the more general question.
Thanks in advance.
Over the course of 2 days or so, it became clear the peaceful fish was extremely aggressive with the new addition, and that this behavior wasn't going to change; rather, one had to assume it was going to kill the new addition. (My LFS advised to remove the instigator from the tank.)
Either the peaceful fish was an unusually ill tempered specimen, or it had some distinct issue with the new fish that didn't seem to have anything to do with any factor you might name (territory, order of addition, size/maturity, coloration, etc.). Certainly it did not seem to have anything to do with any factor I could discern. The peaceful fish was just highly aggressive, at least with the new addition, and not with the other inhabitants.
I have read many postings, but I wanted to ask directly and see if anyone shares information that might be more clarifying.
How useful should we consider the aggression ratings commonly assigned to fish?
Part of the reason I ask is that I have wanted to stock a "semi aggressive" fish, because I like the fish. But I'm concerned about such a fish in my present tank. If these ratings aren't worth much, I'm inclined to add the fish (last fish to be stocked), in part since many relate good experiences with this fish, considering its reputation unjustified.
I am deliberately leaving out any mention of the species I have experience with or have in mind, because I'm interested in the more general question.
Thanks in advance.
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