Fish eggs and Bio-Wheels

Question
Just today I had an overwhelming number of unusual looking eggs appear in my 35 gal freshwater tank. They are round clear balls with white in the middle of them. They first appeared on the glass. They are mainly in big bunches in multiple locations around the glass of my tank. When i scraped them off they stuck to my plants and some smeared and left a white cloud. I know they are not snails eggs because i also have those and they look nothing like these new sets. I have snails, guppies, tetras, 2 Cory, a small sucker fish (do not know the name), and one frog.

also is it ever necessary to change/replace a Bio-Wheel in the filter?

Answer
Hi Hannah:  You can change the bio wheel filter media such as the carbon but do not change the wheel itself unless it is literally falling apart. All of your beneficial bacteria are living in your bio wheel filters wheel.  As for the eggs... we can rule out the guppies since they have live births and do not lay eggs... I would rule out the tetra as well because they are very difficult to breed and the odds are its not them. That would leave the two Cory cats, sucker fish, and one frog.... I would say it is not the frog because it doesn't have a mate (unless you just got the frog and then... it could be the frog.) Frog eggs are laid in one big bunch and they look similar to snail eggs.  Catfish have been known to spawn without a mate perhaps it is there way of attracting a male catfish that might be near by.  I would assume it is the Cory catfish since they breed fairly easily in the captivity and there are two of them... so keep your eye on the eggs and see what happens... let me know... dave