2 dead glo-light tetras

[sancyk]

Hmmm...

In the past two days, I've had 2 glo-light tetras die. One day, they appear fairly healthy, the next they are floating at the surface.

Other than fin damage from other fish (see [Only Registered Users Can See Links.]), they looked fine until today. Maybe it's just my imagination but the two that died appear to be darker than before. All six of my glo-lights were fairly transparent but the two that died are much darker with some black coloration on their backs, as shown in attachment.

I've searched the net to see which disease this could be but I have not found anything. Anyone have any ideas ?

One more glo-light appears to be on it's way out. it's sticking close to the bottom and didn't eat tonight.

Should I treat the aquarium with something to help the remaining fish ?

Should the other glo-lights be removed just in case ?


Water parameters are fine and have been for several weeks.
nitrates: 0
nitrites: 0
pH: 7.5
GH: 2
KH: 3
temp: 25C

20% water change done twice per week.

20 gallon tank
6 black phantom tetras
6 serpae tetras
6 glo-light tetras (now 4)

[gm72]

The red serpaes are likely the cause of the trouble. You pretty much have already answered your own question though. You stated there was fin damage from other fish. Please understand that this is not good and is not normal in a healthy and happy community tank. This is not likely any disease process.

[sancyk]

The serpaes only caused minor fin damage during the first few days they were together. They have lived together quite well for about one month now. The majority of the fin damage was caused by blue tetras during a 12-hour period. I removed the blue tetras as soon as i noticed their very aggresive behaviour.

[gm72]

I didn't realize there was a gap in time between fin damage and death. Not entirely sure what is happening then.

[sancyk]

Just read this on another thread: "You could take out a little gravel, but you could only take out a thin part of the top. If you dig into the gravel deeply, you'll release bad stuff into the water that may kill fish."

My last vaccuming was a little agressive and i did go down to the glass bottom with my vaccum. Can this cause problems with some fish ?

[gm72]

I strongly disagree with the statement that deeply stirring gravel will result in fish death. Nonsense. I changed one of my very well established tanks from gravel to sand without even removing the fish. Zero losses.

[fishfanatic33]

Yeah what is in your gravel is already in the water so stiring it up should not do anything

[sancyk]

Just did another vigorous vaccum and a 25% water change like i always do.

Typically, i run my vaccum on the top inch of my gravel bed. This time, and the last time the 2 fish died, i went down to the glass and under my stones.

Well, woke up this moring and two more dead glow-lights.

Stirring up the gravel like that must be doing something bad to the water...but i don't know what.

[Augus]

Hard to say 100% cause from deep gravel cleaning, since you mention before other fish is looking bad and ready to die aswell.

[sancyk]

the two that died seemed to be fine but maybe the vaccuming brought on just enough stress (chemical, biological, physological or any whatever else can stress fish) to take then over the edge.

Next time i do a cleaning like this, i'll do a water quality test before and after the vaccuming to see if there is any difference.

[shockshockshad]

Check the pH of your tap water. Myabe they are very different so they die after you change the water.

[gm72]

Great suggestion, Shock.

[sancyk]

that's possible. I know that my water is very soft and that a higher hardness level would control the pH a little better.