Mammillaria crinita subsp. wildii (Fishhook Pincushion Cactus) is a solitary or clustering cactus with dark green, globose to shortly…
Fishhook cactus is a common name for any hook-spined species of the genera Mammillaria, Echinomastus or Sclerocactus. They are small cacti, usually growing up to 6-7 inches (20 cm) high, and are shaped similar to a barrel cactus. They are not to be confused with the fishhook barrel cactus (Ferocactus wislizenii) of the Sonoran and Chihuahuan Deserts. The Fishhook cactus is a large category of around 150 species. 
Good places to see "fishhook" Mammillaria are the Sonoran Desert on the U.S. - Mexico border, and the Mesa Verde National Park. Often found growing in desert and rocky locations. 
The genus Mammillaria also contains "pincushion" and other cacti.
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Care instructions for this genus of cacti vary greatly depending upon the species you select and how you choose to use this succulent plant.
Rugged outdoor plants require very little care. Keeping a cactus Indoors is another matter entirely.
When you keep indoor cactus, be sure to set up a sunny location in a room with a south-facing window during the winter time.
This setting provides the most sunlight. A window location is typically a bit cooler than the rest of the room, and this cool temperature during the winter months is necessary to spur Mammillaria to bloom during the growing season.
In the spring and the summertime, vary the location to provide your cactus the most light and heat.
Giving your plant an outdoor vacation in direct sunlight is a good idea.
During the growing season, let the top couple of inches of soil dry out before watering. Water the plant thoroughly, allowing excess water to run off. If your plant has a drip tray, be sure to empty it. These plants should never stand in water.
In wintertime, cut back on watering. You should only water about once a month, and then quite sparingly. Just give the plant enough water to prevent having it shrivel up. Be sure to keep your plant at about 50° degrees Fahrenheit during the winter and provide plenty of light.
You can fertilize your Mammillaria with a specially formulated cactus fertilizer or a very weak solution of houseplant fertilizer that is low in nitrogen and high in potassium and phosphorus.
Don’t overfeed your cactus as this will encourage green growth and discourage blooming.
When you repot your pincushion cactus, you can use a prepared cactus/succulent potting soil, or make up your own cactus mix using a combination of one part potting mix one part coarse builder’s sand and one part loam.