livestock not so happy......

[gp125racer]

Hi All,

Been a while since Ive posted now but Ive got a question.

Weve had our tank going for just about 1 year now. When we setup our tank, I got rock from lots of sources. As it turns out, we now have a fairly large bright green mantis shrimp in our tank. Ive been trying for a month or two now but everything I try I cant catch him. Ive known we had him in there for about 6 or 7 months now.

Within the last 3 months or so weve lost a yellow tang and a blue tang. The yellow tang appeared to be sick one day and by the end of it he was floating at the top of the tank dead. I have no chiller, and it was fairly warm on that day, and the few previous. Temps were in the mid 80s in the tank.

As for the blue tang, we just went missing. We just never ever saw him again. Its been almost 4 months since Ive last seen him.

Could the mantis be responsible for killing these fish? The water quality all seems to be within tolerences, and the other fish seem to be doing fine (gobies, gramma etc).

I hope I was able to convey all the important bits in this message, feel fre to ask if Ive left some important bit out

Thanks!
-=gp125racer=-

[LBCBJ]

Well if the yellow tang was floating on the top then you can rule the shrimp out, and I doubt he killed the blue tang. How stable are your tank parameters? Mid 80's is pretty warm, your oxygen may have dropped too low.

[gp125racer]

The params have been pretty stable for the last 6 months or so.

No big spikes of anything, and no blooms of any type either like the first 6 months was filled with ........

Thanks for the quick response.

-=gp125racer=-

[reefshadow]

i doubt it, especially when there is smaller prey available like the gramma and gobies.

if all the other params are/were fine, then Brent's theory is a good one. tangs are really susceptable to lowered o2 and ph, and the two often go together during the dark cycle in a tank. ph and oxygen become depressed to a degree because the biological processes -photosynthesis- that utilize the co2 and increase oxygen stop or slow to the point where the o2 level falls and co2 begins to climb. elevated co2 levels lead to lowered ph, esp if alkalinity is not up to par. so then you have a double blow to fish that are adapted to a high stable ph and oxygen at saturation, and it can kill them fast, with no prior warning.

there are lots of ways you can help combat this problem if that's what happened to you.

now catching that mantis is another story, lol

[gp125racer]

In talking with my wife she pointed out that it was the day after the heat wave stopped we had the problem with the yellow tang. So we had 3 - 4 days of elevated temps say 87 - 88, then when we had the issue Id say the tank was in the 83 - 85 range. It normally runs 77- 78.

reefshadow, if this is what happened to me (which Im thinking more and more it did), what are some good suggestions to combat the situation?

I was thinking a chiller?

-=gp125racer=-

[gp125racer]

My water params are normally:

temp: 77 - 78
ammonia: right around 0.1 (just barely detectable in my tank)
Alk: 8dkh
Salinity: 1.027
pH: 8.1 - 8.2
Phospate: undetectable
Calcium: 450 - 500

[reefshadow]

a chiller would help with the temp issue, but temp is only a contributing factor to the o2 problem b/c water at higher temps has a harder time keeping o2 at saturation. there are lots of other -cheaper,lol- things you can do to keep your ph and o2 more stable, including

setting up a refugium to grow macro algae and lighting it at the opposite time from the tank, that way there is always photosynthesis going on somewhere to help keep ph and o2 up.

making sure you have more than ample water movement on the surface of the water to help release co2, skimming aggressively to help blow off co2, and thus help keep ph up.

introducing a fresh air source in the house. new construction especially is usually built very tight and you can have rather elevated co2 indoors from people breathing all the live long day, fires in the fireplace, ect... some folks use a fresh air line on their skimmers. i just keep a window cracked an inch.

dripping kalk at night to help keep ph high and stable.

keeping the top of the tank open for better exchange

getting alk up to combat swings in ph. yours isn't bad, but alot of folks like it up in the 10-12 range. i think nsw values are 7ish?

there's probably more maybe some one else can chime in here.

if you arent already running a fan blowing over the surface of the water, you may be suprised how much that can help with the temp issue.

of course this is only a theory of what happened to your fish, but it's a valid one for sure. i think it's why alot of the time you find dead fish in the am.

i notice you have some detectable ammonia. maybe you are also having a very prolonged cycle? from the dead tang perhaps? salinity is also a tich high, but not terrible. ph looks good, but you may want to test it right before the lights come on.

good luck!