Why is my guppy suddenly very aggressive and hanging out in the? top left corner of my tank?

Question

I have a 10 gallon tank that is on 29th day of cycling (is it ever going to be over?!?) Ive been doing daily water changes to control my nitrites as they have been sitting between 0.5 and 1. Ammonia is OK. Since yesterday morning one of my male guppies who has never been aggressive is suddenly hanging out in one corner at the top and protecting that spot like crazy whenever any of the others come near it. He has had something stringy looking around his anal fin since yesterday (i dont think it's poo) Could his fin be torn? Ive never seen a torn fin before? One of my females is also being a little more aggressive than usual. What could be going on?. I have 2 males and 2 females, I know I need more females but I dont want to introduce more fish since my nitrites are still high. Keeping the lights off seems to help, he comes out of his corner more then.

Answer 1

Your daily water changes are hindering the progress of the cycle. The nitrites need to raise to decent levels in order for the next set of bacteria to establish. Once they are present they will process the nitrites into nitrAtes. Then it is best to do weekly water changes.

Their behavior is most likely due to stress. Fish act in odd ways when stressed out. Once the cycle finishes, the fish should go back to their normal peaceful behavior.

Answer 2

You're definitely thinking smart about not introducing any more fishes right now.  

difficult to diagnose without a picture.  There are tons of resources out there to help you figure the specific problem out and how to treat it.  This might explain why your fish is so stressed, and the sudden change in behavior.  

If you do decide that a parasite (or other disease is a problem), you might want to put your guppy in a quarantine tank to treat it (invest $15 or so at wal-mart), just so that your healthy fish will not be stressed further... Chemicals might agitate their state since your tank is still cycling (I applaud your patience!)

It seems like you're already keeping an eye out on the others, too, which is a good, so you can catch whatever this is if it starts spreading.

Best of luck!

*Edit Re: the rest of your information*

Yeah, I know it seems early to have parasites, but it's not uncommon for them to hitch a ride from the pet store.... often fishes don't show any signs until you get them home and have had them a while.  

I have managed to quarantine a good-sized fish in a 1 gallon before, so you should be alright..... Fill it about 1/3-1/2 way with some tank water, then the rest fresh water, and move your affected fish just like you were introducing it to the initial tank (acclimate it to temperature in a baggie).  Note, this is if your fish actually does have a parasite or disease, this way you can actually treat it without affecting your other healthy fishes.

If you decide it's definitely not anchor worm, there are a bunch of good websites out there to help you diagnose disease & parasites and find the right treatments. One book I recommend (if you decide to really stick with aquaria) is "The Complete Aquarium Problem Solver." It's got some awesome and easy-to-use troubleshooting in there.

-Daily water changes are a good bit much, since you do want to allow the "good" bacteria ample time to actually grow, I would reduce them to 20% 2-3 times a week.  It's difficult to get the balance just right of leaving water for the bacteria AND changing it to control nitrates/ites, but slow down a little bit and you'll see things work out.

Your fish are not going to die immediately if you spread out the water changes; guppies are fairly hardy, and although they'll be stressed out for a bit (and at worst you might have a loss or two), overall they'll be much better off if you slow down your changes.

And, well, freshwater tanks are relatively easy, at least, once you get them cycled and have a good stable system going on.  Remember, though, just like care of ANY animal, it takes some effort and practice to make sure your little guys are as happy and healthy as possible.  Totally worth it in the end.

Answer 3

He can be sick,or it is just normal.All fish attack other fish every once in a while.Its should be normal.My fish fight evrey once in a while.So dont worry,but if it continus you should just take him and replace him with another tank.Or just keep him in there if you dont mind a fish dying.

                                       hope this helps,

                                              -Jacob

Answer 4

one of the females had babys or sumpthing and the males protecting it mabye?

Answer 5

oh.. its worse than i thought, hes joined a gang..... whats worse hes becoming a bad influence on the other guppies, possibly even promoting suicide with the spilling top left corner. There is nothing you can do, hes to far gone, sorry.. :(