Copepod Swarm???

At about 10:15 pm, after my lights had been off for a couple hours, I glanced at my take and saw what I thought was a lot of debris floating around. I looked closer and thought they were clown fry. But, upon an even closer look I saw it was thousands of "bugs" swimming around. They looked like a swarm of gnats and were attracted to my flashlight.

I took a video of them, but the "bugs" are blurry so the video really only shows their behavior. At the time I saw them I had no idea what they were, but after a bit of research I found that they are probably copepods.
The critters have a slightly elongated and bent shape to them, a tail-like appendage and what appeared to be two antennas.

Again, Im pretty sure these guys are copepods, but I wanted the 3reefers to weigh-in. Oh, and some were about 8mm's long! Most were about 5mm.

Also, if these are copepods, what are they doing? Are they feeding, or breeding? Im guessing feeding, but Im not sure.

YouTube - IMG_0332.MOV

29 gallon DT
10 gallon sump/fuge (DSB - oolitic, some LR and 3 Mangroves)
60lbs or so of live rock
in-sump skimmer with nice skimmate
heavy bio filtration/live rock
HOB refugium/gutted skilter 250 filled with macro and ceramic bacteria rings and 1 chemi-pure elite 11.74oz - lit by a bright southern window during the day
9.5 mag drive - split return
600 gph CPR overflow
Koralia Nano
150w MH - 10,000K + 48w t5s (Bulb 1 - 460nm, Bulb 2 - 420nm)
temp 79
Mg 1200 - trying to raise
Ca 360 - again, trying to raise
dKH 10
Nitrates 0
Phosphates 0
Ph - 8.0 - trying to raise

Tank Mates - 2 mated Ocellaris - female misbar, Big Seabee Anemone, 3 strip damsel, falco hawkfish, yellow clown goby (willie!), target madarin (4 1/2 months and going strong) - all soft corals, 20 hermits crabs, 20 large snails, 100's of tiny snails

 

those look to big for copepods.. they are probably clown fry.. Mine do it all the time.

 

Your description sounds like amphipods.

 

Becase of their size I thought they were clown fry too, but these guys can swim well. This seems to distinguish the "bugs" from the fry because the fry are planktonic after they hatch. However, I could be totaly off the mark.

Also, I've hatched and raised my clowns and they have never been this numerous. I suppose the current jostling them around could make them look like more.
I'm going to observe the tank for the next couple of nights to see if they come back. If so then should know for sure they're not fry.

Thanks for the input Bama

 

i agree with amphipods

 

The bugs were definitely in the size range of you regular amphipod, but I have lots of amphipod and am very familiar with what they look like.
I love to whatch the little guys scuttling around doin flips and chasing eachother. Back to the point, these guys don't look like amphipods. When I googled copepod images and videos they were, as far as I could tell with the naked eye, an exact match to the image and the behavior.

I could be wrong, but I really don't think the "bugs" are amphipods but I will look closet next time with amohipod in mind in order to distinguish them for sure.

Thanks 2in10

 

Actually Bama, I think your id was correct. My clowns are breeding, I guess I just never knew the little guys could swim that well. Obviously not good enough to stay out of the sump and away from the return. But still, they have some swim in them.