rescue and reproduction

Yesterday I looked in the angelfish tank and saw something dark fluttering in the bottom of a filter uplift tube, right above the spot where airflow comes up from the sponge. I first thought it was a piece of leaf- how would it have got in there? Then looking closer I saw it was a fish- one of my tetras! Wriggling desperately, but all efforts must have pushed it further down the tube. "Ohhh- fish! what did you do?!" I put my hands in to swing the uplift moving the sponge base horizontal near surface so I could take it apart. Gave it a jiggle and the tetra swam out. Seems unharmed. I'm guessing they were spawning again, and during one of the excited spirals at the surface, this fish turned sharply downwards mistakenly into the uplift. In fact after I released it, several other tetras kept swimming up very close alongside the one that had been stuck. The human assumption: Oh, they're comforting it! or welcoming it back! but I think they were just continuing the spawning activity.

I think my white clouds in the window tank (all alive this morning!) are going to spawn too. The largest one looks particularly fat and square in the stomach- it must be a gravid female- and I saw several of them creeping low through dense areas of plants, a smaller minnow swimming in front of the female quivering its fins. I recognize the gesture from when my cherry barbs used to spawn.