What Is Going On?

[TylerFerretLord]

Alright, I've had a big problem with my tank for the past week days.

Since last monday, my fish have been spitting out what I feed them. I assumed they were constipated(as I had been feeding more than usual so the fish that was being bullied could eat more), so I fasted them for two days. They were still spitting out after that. During that fast one of the platies had some columnaris, buut it went away on its own.

On thursday the fish started to hang out at the surface. They have not stopped.

Yesterday, about 30 platy fry I had in a net died. A fry that was close to being released also died. Today, my pleco is upside down on the substrate, close to death. These fish had no signs of illness beforehand, other than suddenly being sick/dead.

I have no clue what is going on. The fish show no outward symptoms of illness at all. The last death I had was two months ago when the male platy died suddenly when he was fine the previous day. The same happened a month earlier with his two females.

TEMP: 80F
Ammonia&Nitrite: 0
Nitrate: Low
PH: 6.8 last time I checked
Water changes: 30% weekly, more if I have the time
Recent changes/Additions: A month ago I tried to add ghost shrimp, but they died as I had used copper previously. My water was cloudy for almost three months, but it is clearing up. Nothing since then.
Eqipment: Heater, HOB filter, Undergravel filter, 24inch fluorescent tube lighting
Stock: 1 brstlenose pleco(male), 4 platies(all female), 1 swordtail(male)

Please help! I don't know what's going on with my tank, and it is really stressing me out to think I may be doing something that is causing these deaths.

 

[Colin_T]

fish gasping at the surface can be from low oxygen levels or an indication that something is wrong with the water. It could be ammonia, nitrite, etc, or chemical poisoning from an introduced substance.
Do you use a bucket for water changes and is it only used for the fish?
Do you use any flyspray, perfume, deodorant, etc near the fish tank?
Is there anything in the tank that has not been bought from the fish shop, ie: an ornament or decoration?
Do you have anything on your hands when you clean the tank, moisturising cream, grease, etc?

 

[TylerFerretLord]

fish gasping at the surface can be from low oxygen levels or an indication that something is wrong with the water. It could be ammonia, nitrite, etc, or chemical poisoning from an introduced substance.
Do you use a bucket for water changes and is it only used for the fish?
Do you use any flyspray, perfume, deodorant, etc near the fish tank?
Is there anything in the tank that has not been bought from the fish shop, ie: an ornament or decoration?
Do you have anything on your hands when you clean the tank, moisturising cream, grease, etc?

Bucket is fish-only.
No sprays used within 6 feet of the tank, but used in same room, and then only air freshener when it is needed occaisonally.
No non-fishsafe stuff in the tank, and I rarely put my hands in the tank. I don't remember the last time I did, actually.

The pleco was dead when I turned the lights on.

 

[Colin_T]

possibly check the temperature with another thermometer just to make sure the heater isn't playing up and cooking the fish.
I gather there is plenty of surface turbulence.
Did you do any work on the tank a few days before Monday?
When was the last water change & gravel clean done?
Do you have blue gravel by any chance?

 

[TylerFerretLord]

I'll do the temp thing.
No work. I don't like putting my hand in the tank.
I did a change on friday.
No blue gravel.

Two of the platies are dead, and another is not looking so good.

 

[Amunet]

If one had columnaris, it'd probably be a safe bet that the rest of them might have a bacterial infection as well.
I'd start the tank on an anti bacterial med such as triple sulfa, or maracyn 1 & 2.

 

[Colin_T]

any chance of a pic of the sick fish?

you may as well try treating like Amunet suggested above.

Do any partial water change and gravel clean before treating. This will remove a lot of the organic matter and allow the medication to work better. Make sure any new water going into the tank is free of chlorine an has a similar temperature & PH to the tank.
Remove any carbon (black granulated substance) from the filter before treating.

To work out the volume of water in the tank
measure Length x Width x Height in cm
divide by 1000
equals volume in litres

When meausuring the height, measure from the top of the gravel to the top of the water level. If you have big rocks or driftwood in the tank, remove them before measuring the height.