I HATE my Killer Congos!

[ameliaaahx]

So, it turns out my congos are murderers. I have 10, 1 male and 9 female (swapping some females for some more males in a few weeks).

A few days ago I added 6 Julii Cories, about 2cm long. That's the only size they get them at my LFS. Now, there is only 2 left, and one of them is looking like he probably won't make it through the night.

I've watched the congos. They chase the cories and tear at their fins whenever they come up to the surface. I give the cories sinking pellets and they're always gone in the morning but I suspect it's my pleco (currently the only fish who has ever survived being in a tank with the congos) who has been eating them. I've looked into other things being the cause of the cories death -- water parameters are all good and I acclimatized them to the tank the same way I usually do, which has always been successful. I've been fishkeeping since January this year (which I know is not a very long time, compared to a lot of you guys!) but in that whole time the only fish I've ever lost is a Golden Honey Gourami who got beat up by a swordtail. Now I've lost 4 (which will probably be 6 soon) in 3 days. Currently, my only option is to put them in my already heavily stocked 30gal.

I feel absolutely awful for putting those poor Cories through that torture. It has led me to resent the congos so much. I don't know what to do. My LFS pretty much only stocks small/baby fish, and I have a pretty sure feeling that the congos are going to harass and most likely kill anything else I put in there with them, unless it's something else as tough as guts, and that means pretty much dashing all the ideas I'd had for my tank.

I had been told and read that congos are a very peaceful community fish, and now I just don't know what do to! I know a lot of people keep Cories with ANYTHING and that they're a great, tough wee fish for beginners. I don't know what to do. I can't return the congos, I got them too long ago. I don't know whether to get more fish, I'm too scared that they'll kill anything I put in there with them.

I don't know what to do!

[pjaldave]

My congos are peaceful, they only look like they are chasing the cories when the cories "dart" into the surface and back to the bottom, which all (or most) of my cories do when they need oxygen. Dart meaning really fast.

Did you in anyways quarantine the new cories? If not, then I will not blame the congos solely for killing them.

[ScottishFish]

Jeez you have some angry fish there, I don't really know what you can do if you've tries everything else :scry:

[escamosa]

I'm really sorry about your fishes, Amelia. But don't beat yourself up about it - this kind of thing happens to nearly everyone. It sounds like your Congos have really got control over that tank at the moment. How about we try something to see if we can settle these little terrors down a little. Congos can become quite shy if their school is smaller than what it should be - actually most tetras will be a little shy if the school is small. How would you feel about splitting the school in half for a little while? What I'm thinking is that you could take the Swordtails, Kuhli Loaches, or the Neons out of your 30g tank, and put them into the 70g. Then take 5 of the Congos from your 70g, and put them into the 30g. What I'm hoping for is that the Congos that are left in the 70g will turn a little shy, and allow you to introduce the other fishes that you would like. The other 5 Congos that you put in the 30g shouldn't cause any trouble, because they'll be the new guys, they'll be a small school, and hopefully be a bit shy as well. Once you've stocked the 70g tank with some of the fishes that you would like, feed them up, let them grow a little, and claim a little spot in the tank of their own, then slowly introduce the rest of the Congos that you're holding in the 30g tank back into the 70g tank to make up the nice school that you had. thumbs2:

[ameliaaahx]

Thanks for the replies, guys. No, I didn't quarantine them. My new quarantine tank smashed the other day in an earthquake. Absolutely kicking myself. Why did I leave it on the edge of the counter? Rookie mistake. Waiting for insurance to pay out.

Wow, great advice escamosa. I have temporarily moved the remaining Cory into my 30g where he wont be picked on. I think I'll get some more and grow them out in there til they're big enough to look after themselves and then move them, but in the mean time the guy at my lfs recommended I buy one or 2 cheap platys or something and introduce them to the tank and watch to see how the Congo's react. HOPEFULLY it was just the small size of the cories which provoked the Congo's to "hunt" them. If it turns out that the Congo's are going to attack anything I put in there with them I don't know what I'll do. Proceed from there, I guess.

[CrunchyLeaf]

Don't feel bad. I know it sucks to lose fish but we all have to learn. You had no reason to believe you would run into this problem.

You are positive that the Congos killed the Cories right? I know you said you saw them chasing the cories, but a previous poster indicated this may be a normal, non-aggressive behavior. Did the cories have abrasions, torn fins or missing eyes when you found them?

The only reason I bring this up is that I would hate to see you get tunnel vision on the congos and miss another problem in your tank. Seeing as how cories are susceptible to problematic water conditions lower in the tank, you may want to keep a close eye on those as well.

Sorry about your QT. That sucks :(

[escamosa]

Thanks for the replies, guys. No, I didn't quarantine them. My new quarantine tank smashed the other day in an earthquake. Absolutely kicking myself. Why did I leave it on the edge of the counter? Rookie mistake. Waiting for insurance to pay out.

Wow, great advice escamosa. I have temporarily moved the remaining Cory into my 30g where he wont be picked on. I think I'll get some more and grow them out in there til they're big enough to look after themselves and then move them, but in the mean time the guy at my lfs recommended I buy one or 2 cheap platys or something and introduce them to the tank and watch to see how the Congo's react. HOPEFULLY it was just the small size of the cories which provoked the Congo's to "hunt" them. If it turns out that the Congo's are going to attack anything I put in there with them I don't know what I'll do. Proceed from there, I guess.

Wow, you can't win a trick! At least it was just a tank that was broken and not yourself. When are these earthquakes going to give up! There's been so many!

By all means try the Platies if you like, but keep in mind what I have said to you about dividing the number of Congos. They've really got their "strength in numbers" thing going - which is great when you want a good school of fish - it means that they will stick together and look great as a school. I honestly believe that the size of the Cories wasn't a big factor in the problem. The problem lies within the Congos. I think they've been in the 70g, all on their own, grown brave as a school, and when they've notice the intruders, they've jumped on them. It's perfectly natural for most fishes to display some dominance towards newcomers - to say, Hey, this is my area, know your place. It's just unfortunate that some of them take that dominance to far. Good luck with it! thumbs2:

[ameliaaahx]

Thanks guys. I'd considered that maybe my tank wasn't cycled properly because I know bottom dwellers are often the first to suffer, but there's a small Pleco in there which seems to be doing great. I would have thought that if it was something like that he would have suffered.

An update: the remaining Cory now appears to be happy and eating in the neon/kuhli tank. I also followed the lfs advice and very hesitantly added my 3 female swords to the Congo tank. No aggression whatsoever. I'm hoping that it was just the small size of the cories which provoked the attack.

I think I'll leave the swords in there for a while to make sure there is no more aggression, and get some more cories and let them grow out in the neon tank. Then hopefully do a swapsy when the cories are a bit bigger. Thanks SO MUCH for all the help and advice. Any other advice would be greatly appreciated! Was wondering what else would be safe and a good addition to my 70gal?

[escamosa]

You could have great fun stocking that 70g. One of my choices would be a species of Dwarf Cichlid. Bolivian Rams (my favorites :ssmile:), German Blue Rams, Keyholes or the Apistogrammas. I think they make a really nice addition to a community tank! thumbs2:

[ameliaaahx]

Actually Bolivian rams were definitely on the list of things I'd like to add. :) Other things I was thinking about were Pakistani loaches and a group of koi angels. The lfs recommended maybe a rainbow shark as something which would stand up to the Congo's and the angels when I add them but not really sure about that. Think I might actually leave my swords. In there permanently as they look so happy. :) and maybe put a dwarf gourami or some female bettas in my 30g with my neonatal and kuhlis. Thanks a lot for all your help!! Great to know that there's always really helpful and knowledgeable people here to talk to.

[ameliaaahx]

Neons... autocomplete sucks.