cichlids are a wide-spread family of freshwater fishes.
they are found in south america, central america, africa, parts of SE asia, and even parts of north america.
there are many reasons that people love cichlids so much including the fact that many are very very nicely colored and attractive fish, most cichlid parents (unlike most other tropical fish) actively guard and protect their offspring, and yes.....their territorial behavior is a much desired trait for many people.....it is interesting to observe....making them very "pet" like.
most cichlids are quite intelligent and can often recognize their owner....to the point that they can actually react differently when other "foreign" people are present.
I have read they all are aggressive. Is that correct, or is there a peaceful species of Cichlid?
aggression is relative.....making this question impossible to answer "yes" or "no" .......
another example of this is when you flip on your weather channel.....and the person says "the humidity is 70%" ...........buzz, wrong! PERCENT HUMIDITY IS RELATIVE!!!!
humidity is the ACTUAL amount of water in the air. RELATIVE humidity is a measure of the actual water in the air divided by the amount that COULD be there (saturation potential) X 100..........therefore giving you a percent.
saying that "the humidity is 70%" is meaningless.
with a 70% relative humidity at the equator there is a HELL of a lot more water in the air than a 99% relative humidity at the poles.
kind of a peeve of mine....... back on topic
some are MUCH MUCH more aggressive than others........there is a world of difference between say a red devil and a blue ram........not even comparable as far as aggression is concerned.
rams are not any more aggressive than a lot of other tropical fish, especially compared to a lot of the gourami species.
on the flip side, fish like red devils are extremely aggressive and should only be kept in very large tanks with other tough, large cichlids.
i could type for the rest of the night, but if you are asking if all cichlids are impossible to keep with other fish....than NO, that is not correct....many are very suitable for community tanks and make wonderful inhabitants.
perhaps a more specific question could be answered.
M