Daphnia From Bare Tank, How Is It Possible? Options

[desireless]

I found my fishes in my main tank displaying some signs of gill infection. So without further ado, I hospitalised them in my QT tub. The tank was left fishless but the sponge filter still run. PL lights running on timer also operate as per normal because I wanna keep my wall algae.

Today, which is the fishes' 5th day in QT, I found some organism developed at the surface. On a closer examination they looked like Daphnia. It is different from those I bought from LFS. I assumed that these are Daphnia based on theire behaviour. Those I bought from LFS are pinkish and roundish. But these I found in my tank are longish and orangy in colour...



Direct Link: http://www.rafflesgold.com/desireless/MOV06310.wmv


How is it possible that Daphnia can developed from a tank which was started from bare? In between I've fed my fishes no Daphnia. Only live food which I feed them are the bloodworm cube... are they responsible for the developement of daphnia too??

How come my tank always come with live oraganism? There was once live bloodworm, then Planaria. Now having removed fishes frm my tank, it is infested with planaria and daphnia

[desireless]

As I do not have any mechanical filter in my tank (OHF or canister), my tank is always very "dirty", in a sense. Whenever the fish is having big (shitty) load, the sponge filters will not be fast enough to act on the poos. Hence i can constantly find particles floating in the tank water. I thought that this can be very stressful to my fishes.

I face outbreaks of planaria every now and then. My fishes are TOO pampered to feed on these planaria. I figure that the planaria outbreak and the floating particles caused my fish to display irritated gill symptoms (but that's my guess). And because of the abundance nutrient in the water, it encourages micro-organisims to build up and probably deplete DO in the water...

But what I wanna asked is... how does the Daphnia colony build up by itself? : Surely they must have come from somewhere (but definitely not from out tap)?

PS: Wah.. I didn't know the music is so loud! I have my PC speakers mute all these while... It is 天涯歌女 by 周璇. Super pop in 1937. was playing it when I took the clip...