Is this the rarest cichlid or fish?

Ptychochromis insolitus is an ugly beast but with a handsome profile. It is a beast in its behaviour, which may explain its rarity. Indeed when tbe species was down the last three individuals, one female and two males, a male promptly went psycho and minced the female who sadly didn't didn't survive. However, due to a worldwide search and a trip to Madagascar, 18 individuals were taken from a stagnant puddle and these represent probably the only surviving individuals. Luckily these are residing in an aquaculture facility in Tana where a spawning has occured giving some hope to the survival of this species. I am lucky to have kept these cichlids and am one of only a handful of people to breed them. Sadly, these fish are unlikely to make it to the hobby. However, if they do make it, they are best kept like Tropheus, in a large group in a large tank. Males over time will grow to as much as 12" with females rarely reaching 5. Spawning begins at 2-3 inches though they are by no means prolific - 50 to 60 eggs being the norm. Fry are very delicate and susceptible to die off. Adults on the other hand are pretty hardy but very murderous. The future looks very bleak for this, possibly the rarest fish in the world. However, it is hopeful that they can bred in Tana in sufficient numbers to allow reintroduction into a more pristine area.

Petrochromis polyodon - the most aggressive cichlid?

Petrochromis polyodon is a behemoth aufwuch feeder from Lake Tanganyika. Similar to a giant tropheus and evelotionary comparable to Lake Malawi Petrotilapia, this fish can beet any in terms of aggression. A 12" male can liquidate all his rivals in a few hours. So why? Probably because of their need to protect their feeding territory from other species. Their diet is extremely specialised and consists purely of algae and small crustacea. The aggresdion is not limited to males. Females can be just as murderous!
How do we keep them? A large tank - ideally 6feet long or more and in large groups - 30 fish would not be overkill. Say 6 males and 24 females. Food has to be low protein and free from mamillian meat. I use aquarian goldfish food alongside hikari koi pellets. And they eat a lot! So good filtration is needed. Breeding is difficult - they are mouthbrooders for up to six weeks. Broods are small fry are huge but very delicate. These fish are well worth the effort!