I've had a couple of long term experiences with them first in the mid 90's when I obtained 6 at the ACA convention in Chicago, and more recently when I obtained 6 young from aFISHionados here in Winnipeg. Here's what Ibelieve to be true about them from my experience.
In small numbers in a relatively small tank (,<100g) mature fish do not do well. The males will pursue and kill females, even if there are hiding places. It's just a matter of time. This is especially true if they have not been raised together from a small size, have been moved from tank to tank, there are no or few other fish present (you need target fish, ones that can take care of themselves). I have in the last couple of years had really great success with my 'polleni'. I started with 6 - 1.5" juveniles about 2 years ago. They were raised together in a 25g tank with several other similarly sized fish for a few months (until about 2 - 3" - a little chasing about- nothing serious) and then placed in a 180G tank with a mix of other Madagascans (6- P.maculatus, 2- P. oligacanthus, 4- P. grandidieri). When small, they stayed pretty much out of the "big fishes" way. I had lots of driftwood, rocks and plastic plants in there to break up the aquascape and define several different areas. There were the usual squabbles and chasing about but little if any damage resulted. The 'polleni' were last in the pecking order because of their immaturity and small size but always managed to stay out of harms way. They really knew every little "nook and cranny" in which to seek shelter if the need arose. Over the next year,the 'polleni' grew substantially (they ate like pigs) and co-existed really well with both conspecifics and heterospecifics. During that time, all other pairs bred in there. The 'polleni' spent their time looking for "free meals". Then about 4 months ago, a pair of 'polleni' spawned. The male was about 10", the female 7". They were exemplary parents but just to make sure I got fry, I siphoned some out (turned out to be 450-500) leaving a few behind to help maintain the pair bond. They continued to guard the 20 or so remaining fry until they were about 3/4". They have since spawned again and are presently into their second week with a relatively small number (~150) of free swimming fry. The other fish steer clear of the pair, and the pair are not particularly perturbed by the presence of other fish. Out of the 6 original 'polleni', 2 males and 4 females resulted. The fry from the first spawn are presently 1-1 1/2" and starting to darken and showing their blue dots. So, if you can, raise a number (4-8) of them together from a small size with several other cichlids of similar temperment (CAs will do) , once they are more mature and sexing out ( 3-5" - males are larger, about double the size of the females), provide a large tank (180G+), provide lots of refuges and hiding places along with tall obstacles to break up sight lines, and have plenty of dither and target fish in the tank that can take care of themselves.
They are a magnificent species, well worth the effort. Here's one of my pairs in action
