I stocked my brand 46 gallon new tank after getting the cycle up and running on Thursday. The tank is a mix of about 30 various guppies (6), platys (2), mollies (3), tetras (9, used to be 11- more below) and two catfish. In the three days with the tank, I lost a cardinal tetra, another kind of tetra (not a black widow, but similar looking and I forget the exact name) and a platy. Two of the three were sucked up against the intake of the Fluval 407 filter. (That's really the question - see below). The platy hadn't been moving much for a day, and earlier it died.
I did a water test - no ammonia, no nitrites, nitrates are around 5 ppm
and the pH is between 7.4 and 7.6.
The temperature is 77.4 degrees.
The rest of the tank looks fine (including the plants), but last night so did the 2nd tetra that just died.
My question is, is there any possibility that the filter is too strong for the fish, and it sucked the two up against the opening and they couldn't get off while they were "sleeping" or something? I don't see any signs of disease in the tank at all, and the chemistry seems fine as well. I do note that another of the platys is hanging out in the corner near the heater lots of the time and isn't moving much at all, so I'm a bit worried for that one as well. Or is it more likely that a few of the fish didn't make the transition from the store well, and just decided they'd had enough?