Moorish Idol - Take 2

[Aquattro]

I thought my tank had lots of O2, but I had turned the pumps down, thinking the lower setting plus return pump plus skimmer would do the job, and lost my 3 larger fish. MI first, then the 2 angels. Low O2 is the only answer I have..

[Samw]

Makes sense Brad. Your sump with the protein skimmer was highly oxygenated but that oxygenated water was not coming back into your main tank fast enough because of the reduced return flow. Night time deaths of the highest O2 demanding fish would result when DO levels drop at night. For most the easier to keep and less demanding fish, this would not be a problem.

If I turned off my skimmer tonight and only leave my powerheads and an aquaclear running, tomorrow I will wake up with dead dwarf angels but no problems with everything else in my tank including tangs. Happened every time.

[Aquattro]

Sam, correct. Skimmer is good, but flow back to tank is pretty low. I'm going to rig a small Tunze to agitate the surface at night when pumps are lower

[Bblinks]

Originally Posted by Aquattro

I thought my tank had lots of O2, but I had turned the pumps down, thinking the lower setting plus return pump plus skimmer would do the job, and lost my 3 larger fish. MI first, then the 2 angels. Low O2 is the only answer I have..

Interesting point on the dissolved oxygen level. I will have to keep that in mind.

[straightrazorguy]

Originally Posted by Aquattro

I thought my tank had lots of O2, but I had turned the pumps down, thinking the lower setting plus return pump plus skimmer would do the job, and lost my 3 larger fish. MI first, then the 2 angels. Low O2 is the only answer I have..

Yeah, that's my biggest fear too. I recently bought and installed a Penn-Plax battery-operated backup air pump so I don't lose fish during power blackouts. Sorry to hear about your MI....

[Aquattro]

Originally Posted by straightrazorguy

Yeah, that's my biggest fear too. I recently bought and installed a Penn-Plax battery-operated backup air pump so I don't lose fish during power blackouts. Sorry to hear about your MI....

I only lost fish, could have been a lot worse!!

[christyf5]

smaller mysis? my fish won't eat the heads....

[gobytron]

Anyone have any research on this or is the current theory based solely on 2 board members shared conversation and experience?

Seems like if proven and not common knowledge, should be a pretty important piece of information for the hobby.

[Aquattro]

Originally Posted by gobytron

or is the current theory based solely on 2 board members shared conversation and experience?

I think this is all we have. I haven't read anything else about it anywhere. Assuming enough O2 is present, are they still super difficult? Probably..

My DT has flow enough for surfing across the surface, so we'll see where I end up in this trial.

[Samw]

Haha. I'm tempted to buy a Moorish Idol, put it in my tank, turn off the skimmer for about 2 hours during the day, take a video of the MI dying while all other fish are active, then turn the skimmer back on to see it recover just so I don't have to keep on about it. I've seen it 2 or 3 times before.