Species Notes based on experiences:

The most desired King Snake in the UK hobby currently. The gloss black colour holds serious allure to would be keepers. This species has seen demand surge over the past few years after a period in the late 1990’s where it was regularly bred and sold for very modest amounts. Certain breeders and stores will charge well in excess of £100 for a baby. Because King Snakes are very straight forward to reproduce this bubble will be fleeting with the market flooded with Meixcan Black King snakes over the next 5 years. At least its not more Corn Snakes and Royal Pythons i suppose.      

Score analysis:

Potentially the worst tempered sub species of the ‘getula’ complex.Mexican blacks can remain problematic into adulthood. This will include biting and constricting hands and fingers. Possibly the most food orientated of the American King Snakes. Of course examples exist which are totally tame but enough examples exist which are not to damage their reputation accordingly. Handling the individual prior to purchase would be a must.
King Snakes of all kinds can be nervous, flighty or even aggressive within their own enclosure. Mexican Black Kings are no different. Tail rattling, flattening of the head, bluff striking and excretions from the cloaca are commonly deployed handling counter measures. For the most part this is restricted to younger animals but certain individuals may always put up a fight when it comes to removing them from the enclosure. It can take some considerable time and effort on the keepers part to get the snake to trust them within their own enclosure.  
All American King Snakes are hardy and the Mexican Black is no exception. This subspecies has a long and storied history in the hobby and has proven over many generations to be an adaptable albeit grumpy King snake.
This King Snake has some mass to it when adult. A large animal is surprisingly hefty with a relatively large head for a King Snake. Because of the colour, size and mood this snake can be in the Adult size score suffered here.
The challenge here is finding a Mexican Black King snake that doesn’t eat each meal like it is its last! These kings are eating machines and in truth probably the best feeding snake on the entire website. Over feeding doesn’t always dissuade snakes from their defensiveness and in time can just create obese snakes. The snake in the very top picture is overweight (you can see the creases on the scales showing where it coils.) We have still to meet a Mexican Black King Snake that is a poor feeder.

Enclosure recommendations:

Tub:
  50 ltr but long term may not be appropriate
Vivarium:
    120cm x 45cm x 45cm

Budget rig: -
    30cm x 30cm heat pad
    On / off thermostat
    Digital thermometer to monitor thermostat performance
    Warm hide
    Cool hide
    Water bowl
    substrate

Recommended rig (vivarium only): -
    100w ceramic heat emitter
    Ceramic lamp holder and bracket
    Bulb guard
    Day night thermostat
    Digital thermometer to monitor thermostat performance
    Various caves along the thermal gradient
    Damp hide
    Plants and foliage (live or artificial – your choice)
    Water bowl
    Substrate
    UVB light (8w T5 shade dweller 7% kit from Arcadia or equivalent) (optional)
    Subterranean section to vivarium for further psychological security (optional)

Climate analysis:

This species will alternate its activity levels throughout the year depending upon temperatures. Mid summer the snake will be almost exclusively nocturnal owing to excessive summer highs, in spring and autumn they may be crepuscular (dawn and dusk) and in winter they may become diurnal. In certain areas of the natural range the snake may need to brumate for a short period to wait out inclement weeks. Brumation in captivity is not always required. If you feel your snake is becoming overweight it can be a useful weight control tool as well. With summer temperatures approaching and on occasion exceeding 40°c and dipping to near freezing this is an adaptable species. This is probably why it has such a long history in the hobby.

Conclusion:

The truth here is, yes, this snake is fantastic looking. The hype for us is somewhat misplaced with other members of the species in need of much more attention and favour. The hobby likes what it likes though, who are we to argue? The likelihood is many keepers will want a Mexican Lack until they own a Mexican Black. Rank novices will be put off by their temperament issues (this isn’t a blanket statement – remember there will be totally placid examples too). We can’t help but feel that this is a bubble of popularity and will essentially be a storm in a tea cup and they will have all but disappeared again in 5 years.