I decided to try something different this time…I’d been putting it off but figured “might as well”.  I decided to try snagging a hatch with the Vossen Aquatics Larval Snagger (aka. Larval Trap).

Thursday night, the 24th, was officially the 6th night post spawn and assuredly I’d get a hatch.  I reconfigured the broodstock tank slightly to allow me to pull all the cords for water current devices in one shot.  I thought about simply using a light timer to turn pumps off before lights out, and then on two hours later, but with the Lightning Maroons, I wasn’t going to risk it. I’d rather stay up late and BE SURE I got everything back up and running.

I set up the larval snagger in the broodstock tank and was sure to get the placement correct – the top of the snagger must reside above the water’s surface, as shown here.

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After that, I made sure to get the air flowing, which runs water through the trap gently, without harming the larvae.

 

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Then, set up the suction cup light, which serves to attract the larvae to the intake of the trap.  Turn off all the lights in the room, and walk away for a couple hours…

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I checked around 4:30 AM and saw that I had snagged a few larvae, but not many.  The nest still looked rather full, and I scanned the tank for wayward larvae, using my cell phone’s flashlight feature.  I didn’t see any, so this was a very weak / small hatch.  It wasn’t enough to really try rearing, so I just figured I’d leave them in the trap and take some photos come morning.  This is what I found when I checked.

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It didn’t seem like nearly enough to bother a run with, so I left the snagger running all day and figured I’d simply try again on Friday night.

Unfortuantely, I might have screwed up on Friday night.  I can’t be sure, but here’s what happened.  The nest looked full most of the day, but I had shifted the light timing just a little bit.  So the lights on the system went off at 2 AM vs. 2:30 AM, but I didn’t make it down into the basement to turn off the filtration until 2:30.  The nest appeared to have hatched significantly before I had a chance to set things up.

I checked at 4:30 AM, and sadly I found one wayward larvae in the tank, and it appeared that the trap had maybe only captured a few more.  Did I “miss” the hatch window Friday night?  Possibly.  I set up the larvae I had captured in a clean BRT with 8 gallons of broodstock water, rotifers, and some RotiGreen Omega, and that was it.  I was gone Saturday night, so wasn’t able to see if I’d get any more on the 8th night.

Overall, based on the number of larvae caught vs. the number of larvae found in the tank, it’s fair to say that the snagger probably did perform well.  I’ll probably try it again on batch 31, and maybe this next time I’ll TEST a timer and trust it to do my bidding.  Maybe a little more automation will allow me to “score big” on a hatch in the broodstock tank, avoiding some of the problems I’ve encountered when artificially hatching.