What fishes can i put in a 30 gallon tank and which i must avoid ?

[minajaguar]

What fishes can i put in a 30 gallon tank and which i must avoid ?
filtration : only skimmer and internal mechanical filtration

can i put tangs or angels or butterflies in small sizes (juveniles) ???

 

[Cheeser]

can i put tangs or angels or butterflies in small sizes (juveniles) ???

dont do it. also stay away from damsels.
i would go with a mandarin or firefish maybe some chromis... clowns are popular

 

[Bifferwine]

Dwarf angels like a coral beauty or flame angel would be fine. The tank is way too small for any tangs, and I don't know of any butterflies that would be okay in a small tank.

 

[ErinCahir]

I would also stay away from a Mandarin in a new tank. Clowns are always great starter fish.

 

[Angelajean]

This is what I have learned about adding fish. Most of it on this forum, from reading, and by unfortunate incidences of death. Heartbreaking and financially annoying as well.
Go SLOW. Slow is fast. Add a fish every month as to not have a huge bioload causing your parameters to go crazy and everything dying. Adding 2 clowns is okay.
Make a stocking list of what you want. Then you need to consider what order to add your fish. For instance, firefish can be a little stressed so I would add it first.
Look at Aquarium Fish: Tropical Freshwater Fish and Saltwater Fish for Home Aquariums They have alot of great info. Check out their nano fish section. It is better to have less healthy fish than many sick and dying fish.

Other people here will have lots more info for you, but I hope this helps.
Angie