new to me

[New_To_Hobbie]

Okay so Like I said before I am totally new to stuff in the fish tank world. I got 2 30 gal fish tank. One tank is cichlids 2 labs, 1 jewel, 1 red zebra, few ugly ones they were tiger stripped and i thought they were kynis(dont remember name) Also i got a blue one with black strips on side, and 1 other ugly 1. I remember they all had pretty colors and brighter. SO there faded and i figure either stress, water quality, or fighting. The tank had a lab die a while ago and he was being in a tank with medicine by cousin said but he died... so sad. And my other tank its a 30 gal too. It has 7tiger barbs, 7 tetras, shrimp when i feed ell, eel, 3 angel fish, 1 puffer, 2 frogs. THey are all standard tanks from walmart. I feed em normal flakes. I dont have test kits to do testing. So i read where water changes can help keep things low. So i do water changes twice a week about 40%. I use in the cichlids tank stress coat and some other good stuff to help tap water. Also i was using melaflix for the fin on lab that died. And i use once in great water cheap walmart tabs that go into tank and desolves.. like the parasites and ph and another 1 . But the cichlids are just so light some days. And sometimes darker. I dont know if its stress or sick. There all eating and play around. Also i got good temp and filters and decos and rocks and bumbles.. and finally the nose part of some cichlids are like blackish like dirty noses.. Is that from all there digging and pushing rocks around? Or is that not good. I think its rock pushing tho.