Mysterious death and 'lazy' black molly

[jamesrm]

I have an odd situation:

My tank at work finished cycling about a month ago, and I increased the stock (Will list below):

Just now, I noticed that I had a black molly hugging the bottom, and that I had a red swordtail belly up on my substrate. Granted, the red swordtail had been looking obviously thin for the past few weeks, but I had no way to isolate or to individually feed. The Molly however was fine. I am pretty sure it is a female, and this could just be the fish getting ready to have Fry, I am just not sure. Both fish were survivors from a fishy cycle. (No serious spikes during the cycle, btw)

My ammonia is barely even registering, and nitrIte and nitrAtes are at 0.

All other fish are acting perfectly fishy.

Current stock in a 30g bowfront:

4 Rainbows
4 Swordtails
2 Black Mollies
2 Neon Tetras
2 Albino Cories

Temp is stable at 78, tank has plenty of O2 from aggressive HoB filter.

Any ideas? I am thinking its more likely just the swordtail finally losing its struggle and that the Molly just happened to be acting odd.

 

[theotheragentm]

I have a black Molly doing the same thing. She hangs around the bottom. This started in the last couple days, but when he does move around, he looks fine. How long has this been going on for you?

 

[jamesrm]

It has only been noticed for about an hour now.

I meant to add in my original post there was an unusual smell coming from my tank. The closest discription that I can come to is a stagnent seawater smell. (I dive alot, so its as good of referance as I can make). This gave me a bit of a scare, and I noticed this yesterday. This could be to the deceased swordtail, if he happened to pass yesterday and I didnt notice him until today, but it looked rather recent.

 

[theotheragentm]

Is it eating? Sometimes sick fish will become sluggish and not eat. I'm relatively new to fish, but that's something I learned. What else is going on?

 

[jamesrm]

That is a pretty thourough discription. It might just be resting, but they normally do that in one of the caves. It is eating just fine, and swims around like normal, but just lays near the front of the tank randomly now.

 

[Fishyfanatic]

It would be cycled if you had present Nitrates. What type of test kit are you using?

Moved to the Unhealthy Fish Forum.

 

[Zagz]

I was going to say that you should have nitrates if the tank is cycled. It is possible that the tank is not fully cycled and the fish are reacting because of that. FF is right what kind of test kit are you using?