This is one of the most up to date care sheets for crested geckos and was written by kate over at button gecko's and all credit goes to her for it. 
Link to original source and to button geckos Caresheet & Button Geckos Please take a moment to pop over to her page and give a like :) 

Housing requirements.

The recommended “off the shelf” requirement for a single adult crested gecko is a 45x45x60 (WxDxHcm) Exo Terra or similar terrarium, with a 45cm cube being your bare min.

If you are wishing to have a live planted setup then attention should be paid to the available space after planting...in this case a 45x45x60 becomes your bare min due to the room required for soil and drainage. If you are considering co-habbing then read further down, But your bare min for housing two will be a 45x45x60 (This is unplanted, for planting, again internal size should be considered) with a 60x45x60 being recommended. You can play around with sizes if you choose to go for a custom built enclosure.

Recommended hatchling housing is smaller at 30x30x45, this is aimed at geckos under 10g, and IMO are only suitable to the max of 20g. Those over 10g can be moved into a large exo but provide multiple feeding stations to start with to ensure s/he is eating. A 9 liter RUB (really useful box) or similar can also be modified with plenty of cross ventilation but as its slightly smaller, i would house no more that a 15g baby in one before upgrading.

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Wooden setups may also be used besides Glass...though special attention should be paid to ensure it is sealed properly to prevent moisture getting into the wood. In doing this it will prolong the life of that enclosure, ill sealed viv's can lead to warping and mold.

Converted fish tanks and plastic tubs are also very popular choices in housing, just ensure that its big enough and has height! You will be more limited with these two options in terms of heating and lighting so bear that in mind when deciding :)
I personally do not however recommend Repti-breeze/fully mesh enclosures. Mainly as they hold humidity very poorly unless modifications are made. 

Crested geckos are starting to be thought as Crepuscular (meaning dawn and dusk) not nocturnal.

For this Crepuscular species you will need to provide LOT’S of coverage and branches throughout the enclosure. Both Plastic and Live plants can be used to decorate, though i recommend investing in a plant grow bulb or Jungle Dawn LED to help promote plant growth if going live.

Fallen wood can be used from outside but avoid anything that is Pine/evergreen/soft wood due to toxins.

Substrates

Crested geckos are a humidity loving species and the substrate you choose can help you maintain this. There are some fears with keepers about impaction, whereas others not so much. With this in mind, it IS personal preference.
Commonly used substrates include:

  • Coarse Orchid bark
  • Eco Earth
  • Topsoil / Compost (must be free of treatments, fert's and pesticides) 
  • Leaf litter/moss/bioactive mixes
  • Lino
  • Tiles
  • Kitchen roll (recommended for hatchlings though can be used with adults).

Substrates such as Aspen and Sand are NOT suitable for this species.
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Temperatures and Heating

Both temperatures and Heating methods are constantly disputed within the crested gecko community. As it stands there are multiple ways of providing heating and a big range of temperatures that you can maintain. Below lists the more common ways to do with temperatures needed for each.
 
  • 30c if offering a basking spot and providing a temperature gradient or lower temperatures.
  • Optimal day time range for ambient (taking into account seasonal changes): 22-27c 
  • Night times: Heating can be switched off, though if the room has a tendency to drop below 18-17c regularly in the winter, I would look into addition heating, if that is the case then a 18-22c night time drop can be used. 

The Recommended Method:  One of the most recommended ways of heating your enclosure is with a Ceramic bulb (75w-100w), in a Dome & ceramic holder, connected to a Pulse or Dimmer thermostat. The aim for this method is to provide a gradient with the top temps (basking spot) being 29-30c and allowing the rest of the enclosure to have a gradient (meaning to have varying cooler temps) running down to allow your gecko to thermal-regulate (pick where they are happiest) as they see fit. A light emitting bulb on a Dimmer stat or Canopy (pay attention to max bulb wattage) can also be used though bear in mind that this should be switched off in the evening. You can also use this method to *bump your normal ambient if you wish to not have as high a basking as 29-30c.

Personally for thermostat & thermometer probe placement: The probes should be anchored to the nearest basking point/branch to the ceramic. 

Those using a small enclosure for younger geckos will need to have a play around with a lower wattage bulb and basking spot temperature. The lack of height compared to that of a 45x45x60cm means that a gradient is harder to achieve or you can go to one of the alternative methods. Not suitable for direct contact to glass or RUB and other plastic modified tub. 

Alternative: Other ways to keep crested geckos include the use of a Heat mat to the outside of your enclosure. Things to note with a heat mat: These are surface heaters only! They will not affect your ambient and as such if your house leans towards the cold side then the recommended method should be used. The are also not a 100% waterproof! therefore always have on the outside. A heat mat will need to be stuck to the side of your enclosure to allow your gecko access and should be stat’ed to a mat stat (basic on/off). This is recommended when using with a modified plastic enclosure.

Probe placement: Personally put the stat probe between the glass and mat on the side, then place your thermometer probe on the inside of the enclosure, on the glass, over the mat.

No heating: There are also many keepers that keep with no additional heating whatsoever. In these cases close attention to your seasonal ambient should be monitored..the classic "room temp is fine" is not always fine, room temp is individual to a keeper, not universal :) . This is still an acceptable way to keep your crestie however this is a debated on method (what isn't with cresties?!) as husbandry evolves and constantly improves. Those that provide heat will remark on the improvement they've seen (in colour, appetite and activity). So I will urge you to think on what YOU want to provide before choosing, try not let money factor in your choices if that's all that is putting you off from any of the options :)

With all this in mind, temperatures should be monitored via a digital thermometer or a temp gun and any heating equipment controlled with a stat.

Please note! the dials on a stat aren't always accurate, it is for this reason that when setting up, you should judge the temp by your Digital thermometer and ignore the numbers on the stat! Also, cheap temp and humidity dials are also very inaccurate and prone to breaking, Digital thermometers are not that expensive and do not need to be reptile branded :) check out ebay and amazon.

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Lighting

Yet again DEBATED! With some keepers opting not to use lighting...but here are some great choices to help with your day and night cycle.

Though Cresties do not need UV, they do need D3 to process Calcium (which UV can provide, the alternative is a supplement).
More and more keepers are experimenting and using UV, with 5% being the most commonly used percentage. Those that choose to use UV have yet again commented on the improvements they have seen with their geckos, with some even openly basking. They give out very little heat so should not be relied on as a form of heating. If you choose UV then please combine with a reflector to get the most out of your tubes! 

Other methods of providing lighting are via a light emitting bulb (if you choose this heating method), full spectrum tubes/Plant grow tubes/ Arcadia Jungle dawn LED (great for those with live plants and promoting growth) and the use of LED spot light or strips (these give off very low-zero heat). Both of these are available in a choice of colours for if you wish to have night time viewing (Red being the most common, with blue close behind)....though i would still recommend that this lighting gets turned off once you go to bed

Humidity

Crested geckos, like I’ve mentioned, are a humidity loving species! This means daily misting via a squirty bottle or misting system. The time of year and temperatures will dictate how often these guys get misted. During the winter this can mean as little as once a day, with the summer as much as 3-4 times! The important thing to remember is that they need a cycle rather than a constant high. This means the enclosure needs time to dry between mistings. 60-80% is the guide used for monitoring your levels. If you wish to visually monitor in this fashion then a digital hygrometer wouldn’t go amiss. Though this isn’t an important bit of equipment, I do however recommend it to new keepers till they get the hang of what’s enough 

Another point to be made in regards to Humidity is that it goes hand in hand with hydrating your gecko (which in turn affects shedding). Though they will use a small water bowl, 9/10 my geckos will prefer to lap at droplets on leaves and branches. If your humidity is not enough then your gecko could start having bad/patchy shed’s that they will need aid removing, as well as the chance of becoming dehydrated.

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Co habitation.

Though these geckos do not require company, they can be kept in pairs of females or small groups. In this case, close attention should be paid for any signs of bullying and a spare enclosure put away in case of separation. Avoid owning more cresties then you could house separately to start with!

They do not always co hab successfully.

Look out for..
  • Consistent chasing
  • squeaking
  • tail shaking and/or Tail loss
  • Injury
  • Biting
  • Weight lose
  • Any behaviour not deemed normal for the individual

When thinking of co-habbing there are a couple of things you can do to help reduce the risk of bullying (though it won’t completely negate it). 

  • Sex should be confirmed. (prior 25-30g of weight, a female sex is only an educated guess, males have been known to develop late and this should be considered before thinking about co-habbing)
  • Match your cresties up in size/weight as best you can.
  • Have a large enclosure.
  • Provide lots of additional hiding places.
  • Use multiple feeding stations.

Please note! All new additions to your household should be quarantined (at least a month but 3-6 months is recommended) as best you can away from your current reptiles to start with! Keep Current reptiles safe! Please see Health for more info.

Co habbing a male and female pair year round should be avoided due to the stress this puts on to the female as well as the need to allow your geckos to cool during the winter months. Females should be at least 40g and 2 years of age before considering introducing a male which is why sex should be confirmed first.

Mixed pairs and groups WILL result in egg laying (though it is not uncommon for the odd lone female to produce infertile eggs). This again takes a lot out of a female (and under the wrong conditions, at risk) who on average will lay one or two eggs every 4-5 weeks….depending on the female, this can mean 5 + clutches per year.

Lastly.. please note that having more than one male per enclosure is also NOT recommended, these guys will fight..and mean it! There have recently been a few cases where people have successfully had male pairs, my opinion? it's few and far between, most definitely NOT worth the risk.

Breeding

This care guide will not have a "how to breed" section i'm afraid...My personal aim is to help new keepers care for the geckos they have first. :)
Take your time and have fun!! If later you wish to try breeding them do it for the right reasons :)
 
Diet's

There are plenty of good CGD’s (complete gecko diets) now available with these guys….gone are the days of baby food! (which has proven to be very bad for them!)

CGD's that are easily obtained here in the UK Via geckodiet.co.uk highly recommend them. 

  • Pangea Fruit Mix Complete (available in 3 Flavours). 
  • Clarks (available in 4 flavours).
  • Black Panther Zoological (BPZ) ....insect based diet that should be used with one of the others.
  • BPZ colourbomb...as above but also fruit flavoured.
  • Repashy
  • Repashy fruit and grubs (50/50 diet).

If it's not on the list above then it'll be for one of the following reasons..
  • Not a complete diet.
  • Not considered a good complete diet.
  • New or no longer available.
  • Various keeper experience has been poor.

Those of you Stateside will be able to order via the makers/producer of each CGD.
Others can try ebay, amazon and contacting gecko diet or the supplier for shipping costs :)

CGD is mixed with a small amount of water till it’s like yogurt and can be served in bowls, milk caps and similar lids. It should be available at all times and replaced every 48hrs.

Geckos can be fed solely on CGD though a mix of live food is greatly recommended for variety. 

Basically...CGD is your Staple, Live your optional additional.

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There are vast amounts of live food you can use if you wish; the general rule is the width between your gecko’s eyes for sizing.

Some insects that can be used are...
  • Crickets
  • Locust
  • Roaches
  • Wax worms (treat only)

Important thing to remember is to gut load any live food, this means feed it and generally look after it right up till it becomes dinner. Live food should also be dusted with a small amount of calcium. 

Those that do not provide UV will want to make sure that it is calcium that contains D3! 

Offer live food once or twice a week, slightly more often for a hatchling if you want. If using crickets then I would remove any left come the morning to stop the little blighters having a nibble on your sleeping crestie.

It should be noted that i personally like provide a milk lid of pure calcium (again - non-UV users will need one with D3) at all times in the enclosure as i have witnessed all regulating themselves to a degree...more so when gravid!

Let’s not forget little treats!
Mashed up ripe fruit make a great treat for your gecko! Papaya, Fig, Pears and various berries to name but a few!

A drizzle of honey mixed with either the fruit or CDG as an occasional treat may also be used.

But be aware…

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The Big food no no's!

  • Citric fruit (ie the orange family and lemon...kiwi is also labelled as a citric.)
  • Banana - fresh banana is a Calcium binder, banana flavoured CGD's has already been balanced to counter the high potassium. Some will use as a very rare treat but IMO you do have many other fruits to pick from.
  • Baby food! This is something people used to do and since proven to be very bad for them. All baby foods have a shelf life meaning they have a preservative, in most cases this preservative is citric acid. big no no. They are also not balanced to provide your crestie with everything they need to stay healthy.
  • Jelly Pots! A recent craze and trend has seen these becoming popular! They are filled with E numbers and citric acid. They have 0 nutritional value and can be addictive for cresties. They were designed to be fed to livefood and inverts NOT reptiles. 

For more information please check out the Diet section :)

Finally! Few  items of interest that I always think is wise to read up on (can be found in the health section).
 
  • MBD (Metabolic Bone Disease).
  • FTS (Floppy Tail Syndrome).
  • Internal parasites and testing.

Reading up on these will help you pick a healthy Gecko and also maintain his or hers health by knowing the signs for the above. A brief covering of each plus useful links can be found in the health section.

Thanks for reading, you've all been magic!

If I’ve failed to please every crestie keeper then...Opps! :P Crested gecko care is a mine field of different information, welcome to the ranks and you have been warned ;)