What am I doing wrong?

[neptuneviv]

Hi,

I've just started up a livebearer/catfish tank. In a fully cycled tank (fishless cycling), I added 4 cory cats (1 albinos, 1 bronze, 2 panda), 3 platies (2 females, 1 male) and 3 male guppies.

The tank is a 14 gal. The water is clean, ammonia/nitrites are 0 and nitrates are under 25 ppm. PH is around 7.8 and temperature is (damn this heatwave) 30°C/86°F. The substrate is sand, with a layer of gravel underneath. The fish get fed flakes (for the livebearers) and sinking pellets (for the cories) on one day and with brine shrimp/daphnia (in jelly "Tetra Fresh Delica", great stuff IMHO) the next. I feed them once a day and I don't believe that I feed much (I tend to underfeed rather than overfeed).

It's been about 2 weeks now, and I've had 2 deaths and a new sick one today. One guppy died within a few days with no visible symptoms. Then a couple of days ago, a cory cat started floating on the surface and swimming upside down. Within 24h it was dead - I inspected it and found no signs of disease. And now I have a guppy that is bent in half sideways (in a "U" shape) and looks like it's got a swollen belly. It's still kind of active, but it's not looking good at all and I don't know if there's anything I can do to help.

Oh, I have noticed that the male platy seems to be bullying. I'm pretty sure he's responsible for nipping fins on the guppies and I saw him nip a cory's tail. I added some Melafix to the tank yesterday to help them heal up. But that couldn't kill a Cory, could it?

So what is my problem? Am I doing something wrong, or is this simply "natural selection" in shop fish, ie, that some fish are degenerate?

Thanks for any suggestions or ideas!

Viv

 

[Alien Anna]

I've also lost fish in this heatwave. Warm water has low oxygen carrying capabilities and guppies particularly seem to suffer in the heat. I've also lost mollies.

Cory's, like all bottom feeders, do have a problem with oxygen levels that get too low. Try putting an air-stone or two in there to really oxygenate the lower levels.

Also, turn off the lights in the hottest part of the day and open the hood (have some water on stand-by to counteract the evaporation. You really need to get that temperature down. However, don't be tempted to dump some cold water in there - the cold shock could kill them.

Another trick I do is to float some of those picnic icepacks on the water. As it causes a colder current of water to drift downward, the fish can get out of the way if they don't like it, but it does help cool the tank down slowly.

When you have the hood open put a room fan somewhere near the tank (not blowing directly over it) and try to cool down the room. It's a good idea to get a room thermometer so you can keep a track of the temperature and put fans on if it gets too hot.

Hopefully, we'll all get through this until the autumn. Then we'll have to worry about tanks getting too cold!

 

[neptuneviv]

Thanks for your answer!

I don't have much experience with fish that rely only on their gills for oxygen, especially in the heat of summer, so I'm not quite. I've only had Bettas until now, and they're surface-breathers, they never seemed to have any problems with heat. At any rate, I've turned the airstone on. I unfortunately have to switch it off when I sleep, as it's pretty noisy (any tips on reducing air pump noise would be very welcome!). I'll try lowering the water temp, too, though fortunately we're supposed to be getting a cool spell in the next days and hopefully that will help with the tank.

I'm still really mystified by this guppy's "U" shape, especially as it came on overnight. If I didn't know better I'd think his back snapped, but he's actually quite mobile. He's still hanging in there and moving around. Could it be he overate and is suffering from some kind of bloating/constipation? Or would lack of oxygen cause this?

Thanks!

 

[Kossy]

is the pH 7.8? thats a tad high. cory cats don't really like the pH to be that high.

 

[Alien Anna]

is the pH 7.8? thats a tad high. cory cats don't really like the pH to be that high.

Kossy, the problem is that many of us in Britain have water coming out of the tap at pH 8.5 or higher. pH 7.8 is actually pretty good!

I always worry about comments to newbies about pH because of the temptation to go the LFS and get some pH Down, chuck it in and kill their fish. Likewise, I worry when newbies are told their water is too hard. I killed more fish trying to get their water "perfect" than if I'd left well alone and just got hardy fish that could cope.

Yes, in an ideal world corys like soft, acid water but we don't live in an ideal world and many people successful keep corys (and even breed them!) in harder, higher pH water. For all you know, these corys are several generations bred in such conditions!

I doubt very much that it is the pH that killed them. The tank has been registering temperatures in excess of 86F and that can kill bottom-feeders for certain! Especially if the filter's a little over-loaded.

 

[neptuneviv]

Yep, I agree with what you say Anna. I live in Switzerland, I get hard water with a high PH, and while it might shorten the lifespan of my fish in the long run beause of stress, it wouldn't cause acute symptoms like those that I've seen. I've tried a product to lower the PH on an empty tank and I got no change whatsoever (the product did say that with hard water it was difficult to lower the PH), so the only option I'd have would be to go buy osmosed water or what have you at LFS and mix it with my tapwater.

The guppy that was U-shaped turned out to have dropsy and died a few hours after I posted, I suspect it had been sick since I bought it (it had been acting odd for a while). I suspect the sick Cory could have had a similar internal infection. I'm reluctant to dose the tank with antibiotics, though (I have Furanace, an internal antibiotic), as it would probably destroy the nitrifying bacteria too and cause ammonia and nitrite spikes.

Thanks for your answers!

Viv

 

[Kossy]

I'm sorry...In australia its actually 7 - 7.2 (Not bragging or anything )