Tank Woes

[Gypsy5]

Hi all, I just wondered if anyone has any ideas about what could be wrong in one of my tanks?

Tank size: 3ft
pH: 7.6
ammonia: 0
nitrite: 0
nitrate: 20
tank temp: 24/25 C

Tank houses black mollies (about 10 in total, most of them are young/small adults). No visible markings on fish just noticed that they seemed to be hiding either in the java fern or at the back of the tank for a while now. The tank is in a reasonably busy part of the house so we thought that it was either us passing the tank frequently or maybe the light in the tank was too bright for them that was causing this behaviour. However, one of the mollies tonight was darting about the tank sort of corkscrewing. We have moved it out of that tank and placed it in a hospital tank where it has settled down (leaning a bit though but definitely calmer).

One thing that did happen about a week ago was that one of the deformed black mollies that we had in there died (we were expecting it sort of as she was getting on a bit). I netted her out and put her in a pot of the tank water until my husband got home to bury her. Within a couple of hours the water she was in was really murky, never seen anything like it. Don't know if this was just her colouring coming off or something else so thought I'd just mention it.

Water changes are done every week (about 20% worth) and a little salt is added to the tank every couple of water changes (not much though). The tank has an undergravel filter as well as a Fluvel 1 internal filter. It also has an air stone and is quite well planted (lights are on for about 12 hours a day).

No recent additions to tank. No exposure to chemicals (we don't spray anything downstairs and the tank has a big wooden box lid on it anyway.

We have now moved all the fish out of this tank and put them into one of our other ones where they are quite active and having a sniff(!) about - a stark contrast to their behaviour in the other tank. We can't work out what's wrong. Could it simply be a case of being sensitive to us walking past all the time?

Thanks for reading.

 

[WILDER]

Cork screwing can mean external parasites, internal parasites, bacterial.
Any fish flicking and rubbing against things in the tank.
Any fish look bloated or skinny.
What does it look like when the fish to the toilet.
Check the fish anus to see if it's enlarged or red inflamed.
Any fish have bent spines.
When you say deformed can you describe it in more detail.

Darting can mean, bad water quality, parasites, stray voltage, toxins, over dose of meds, the fish is dying, ph shock.

 

[Gypsy5]

The fish that was cork screwing is not doing it in the hospital tank which leads me to believe that it's something wrong with the original tank or that they weren't compatible with it for some reason. They were all fine before we put them in there and are all quite active now we've moved them. No flicking and rubbing against things in the tank, no bloated or skinny fish.

Haven't noticed anything wrong with their poo, no enlarged or red inflamed anus. No bent spines.

The fish that died that was deformed was born that way over a year ago. She was a big lady (not fat, just a big specimen) but her tail was slightly bent at its base and it was a bit short. It never seemed to bother her though and she was healthy in all other ways.

Thanks x

 

[WILDER]

Under gravels filters are no good. There outdated now.
Sometimes they can harbour nasties bacteria's and they can get blocked.

I would think of removing the under gravel filter and get another internal filter.

I would read to much into the dead fish in the pot, it could of just been decomposing.

 

[Gypsy5]

Thanks, will probably strip the tank down and start again with it, get rid of the undergravel as suggested.

Fishies are quite happy now except the one that was corkscrewing. She's not doing that anymore but she doesn't look good. Mind you we've had them come out of worse than this so fingers crossed.

I thought fish were supposed to be relaxing...lol

xx

 

[WILDER]

I don't find fish relaxing at all.
Good Luck.