Guppy swimming against glass

[Belltrain]

So I have recently finished setting up my 39 gallon bowfront. I have completed the cycle and currently have 0 ammonia 0 nitrites and little nitrates. My girlfriend wanted a fancy guppy so I let her pick one out. Now this guppy constantly swims up and down the tank wall. Is this a problem. I checked my water quality to see if this was a cause and it was all good perameters. Is this normal behavior? All the other fish seem great. If I buy another guppy as a friend will this deter this?

 

[SnakeIce]

The guppie is chasing his reflection, more guppies might reduce the behavior, but out of a group you may have some that still do it from time to time.

As far as biology is concerned it isn't abnormal behavior. But to answer if it is cognitively normal behavior is much harder to say. I don't know if it is an abnormal obsessive type behavior that is so common as to seem normal or if it is one normal response to hitting a glass wall. (something that isn't normal so go figure).


So, common behavior that might or might not be reduced with more of it's kind. Still recommendable to add more, as long as you consider that having both sexes will come with the likelihood of having babies born.

 

[NeverFadeAway86]

ive had cory cats do this, ive had chichlids do this and tetras as well. Nothing unusual just chasing their reflection

 

[Belltrain]

I was just thinking if I add more he might have someone to chase other than his reflection.

 

[OrionGirl]

Males will chase each other, and potentially rip fins. Males will chase females, with the end result of more guppies. LOTS more guppies, in most cases.

Fish don't make 'friends' like kids on a playground...

 

[Tifftastic]

The amount of chasing and biting at a reflection is a measure of aggressiveness in fish behavior. Fish that do this more than others are those that would generally be considered aggressive and likely if you add another guppy, particularly a male, he will do this to the other to the point of stressing the newcomer and potentially harming him. If you add a female he will chase her non-stop, but will also spawn with her and you will have more guppies than you could ever want.
In most cases, the fish will eventually learn that it is just his reflection and the amount of time he spends doing it should start to decrease over time. However, guppies bred for captivity are typically inbred and from low quality strains, he may not actually have the cognitive power to learn that it is his reflection. I say just wait it out. New research is showing that guppies in captivity aren't necessarily shoaling species, so more fish may not be a good thing.

 

[Belltrain]

Yea friend might not be the best term I was just thinking of ways to stop this behavior. It seems almost stressful to the fish, maybe I'm over analyzing things... I didn't really think about a guppy harassing the other male, I thought they would just shoal together, but maybe I need to rethink guppy aggression.

 

[alan01230]

Ive had a fish tank of one or the other set up since the 1960's and beleive always had some fish that would do this, It is normal imo better than having them just sitting on the bottom.