Do you have any advice?

[SmokinJs]

I set up a 75 gal tank 4 months ago. I had a few fish die the first month, but haven't had any die since. My current water chemistry is pH 8, Nitrites and Ammonio 0, and Nitrates 5. I currently have the following fish in my tank:

Eupterus Catfish
Rainbow Shark
Dojo Loach
3 Plecostimus
3 mollies (1 sunset, 1 dalmation lyretail, 1 silver lyetail)
2 lemon tetras
1 neon (other 4 died the first month, this one survived)
2 black neons (other 3 died the beginning of the 2nd month)
3 long-finned danios
1 peacock eel (new)

I'm using the Emperor 400 filtration system.
When I first started the tank I did 25% WCs weekly for the first 2 months. I have only been doing 10% WCs weekly and a 25% WC monthly. The water seems to stay very clear, and the ammonia levels haven't gone up. Nitrites aren't rising either. Nitrates have been steady at 5 every since the end of the first month.

Do I need to perform WCs more often? I'm new to this hobby and I'm curious if anybody has any advice for me?

[OrionGirl]

Check some other parameters as well. KH and pH specifically--if they start fluctuating, more water changes will help stabilize them. Otherwise, as long as things are stable, you should be fine keeping with this schedule.