no bubbles in freshwater fish tank

Question
hi this is just an easy question but im still curious.

i have a fresh water fishtank 75litres with two black moors and two commets.  
anyway my point is that the brand of my fish tank is aqua one and i've
realised that i only get small tiny micro bubbles in the fish tank. before i use
to get bigger ones coz i think i didn't put much water in the tank but now i
put it all to the brim so wen the water is coming out from the filter it goes
straight in the tank. is this why i don't get bigger bubbles? i use to get tiny
bubbles before but now i hardly see them at all.

my filter/light  etc is on top of the tank

the ten or so holes that make the water come out from the filter go straight
in the tank water so i suppose it doesn't push more oxygen in the tank.

let me know asap

Answer
Anita -

No need to worry about the air bubbles.  It is not entirely necessary.  So long as your filter is operating and cycling the water, the fish will get oxygen.  However, the air bubbles do help out more with breaking down the ammonia and such from the waste in your tank.  The air bubbles from air pumps and stones is a very aesthetically pleasing addition to an aquarium, mostly.  Determine how your levels are and adjust from there.  Keep an eye on the fish also, they will tell you if something is not right.