Is it ok to have little or no lighting at all with midas cichlids, pikes, jaguar's, salvini's, and texas cichlids? Is an aquarium light even necessary?
Lighting is really only for you to see the fish. Having said that I don't mean it's ok for them to be kept in total darkness all the time. Normal room lighting/day light in a bright room is fine. I wouldn't like a tank with no light over it but no it's no a nessesity, just nice.
The only thing you might want to avoid is direct sunlight going into the tank. Again, no harm to the fish per se... but can cause some nasty algae type issues.
No. Direct sunlight can cause multiple types of algae issues, that you pleco... or no other fish... will help with... like green water. Not a problem you want. Possibly even slime algae issues as well.
Natural daylight coming in your windows will not be an issue... only direct sunlight rays, that shine into the tank itself.
Choosing the right lighting can also play a large role in the coloration of your fish that is visable to the human eye. Different types of light bring out different colors.
I use to run the standard light fixture that came in the cheap kit i got my 55 gal with. I later updated it to a dual 65w Compact Flor. setup when i was doing a planted tank and I must say it really made a huge difference in how the fish looked.