Late last night I was downstairs wrapping a few last minute presents. I had turned on a bright desk lamp which stood next to the canister for the filter in my big saltwater tank.
The tank was set up for a spotfin butterflyfish but I had used a school of rainwater killies to cycle the tank. I liked the killies so much, and they were such well behaved companions to the butterfly when he was dime sized, that I let them stay. Now that the butterfly is golfball sized, his meaty diet and sloppy eating habits have greatly benifited the killies and they are thriving with all females fat and all males bright yellow with blue and red dorsals, each defending a little kingdom of his own. I've seen lots of displays and courting but figured the ever prowling butterfly would scarf up any eggs and the flounder would clean up what he missed.
So anyway, I'm down there wrapping presents and I spotted movement inside the filter canister. This filter is actually used as a pump to feed a DIY trickle filter that hangs from the ceiling above the tank. The canister has a foam sleeve which is used as a prefilter from the trickle filter. I've used similar setups over the years in fresh and salt and have often found all kinds of inverts from snails, scuds, crayfish, to crabs and various saltwater shellfish living inside the canister. This time it wasn't inverts though. It was a couple of 3/4 inch long baby killies! Apparently the rich diet of the butterfly and co provided lots of tidbits to fuel a healthy fauna colony growing on the foam pad. Enough for at least two tiny killies to grow and thrive in the preditor free envirnoment. The current is strong inside the canister but I noticed the babies had found little eddies and sheltered areas to rest in when needed. For the heck of it I squirted some ground up flake into the filter intake and immediately the little killies went into feed mode and filled their little tummies right up. Purty kewl!
For now I'm just gonna leave them in there. They can't get sucked past the filter pad and they're obviously getting enough to eat. Soon as I get a chance, I'm going to set up a little 2.5 gal tank I've got laying around for them. I just might add a few of the adult females too and then drop in one of the males when the girls are looking plump and sassy.
I've already got rainwater killies in my big saltwater and my big planted freshwater molly tank. I just might have to add some to my freshwater stream tank and maybe even the swamp!
Funny how for so many years I've been seeing those guys in my nets and never thought more of them then as feeders or tank cyclers. Suddenly they're my new favorite fish!