Mystery Solved! I placed the tank structure prop outside the tank and sifted the gravel. When I lifted it, there it was - the second Pleco (and some fry). Time to gift them to the students.
Thanks everybody.
Thanks. I looked up Corydoras and it does look like our fish. Here's the tank history.
September:
Another class wanted to get rid of tank. I adopted all their fish into my 25 gallon tank.
I already had 1 tiny algae eater (corydoras), 1 pleco, 2 large goldfish.
I inherited the 1 large goldfish...
I came to my classroom today (Monday) and found fry (baby fish). The look like Pleco?
In the tank we 1 plecostomus, 1 asian algae eater (I think), and some Rosy Red Minnows.
The algae eater has been laid eggs twice in the last month but nothing happens.
I put the Rosy Red Minnows in the...