HCA: Hermit Crab Association

I understand that crabs need a source of heat whether it be an UTH or a heat lamp or hood light.

But are lights that provide UVA/UVB rays a must?

To keep the crabs alive for extended periods of time you will need them.

Without UVB they will be have Vitamin D3 deficiency.

Also UVA light helps them remain active and promotes more active feeding for them.

Make sure there is nothing blocking the light from reaching the crabs when you use it since nearly everything blocks uvb light such as plastic or glass tops so you may have to set up something to support the light if you don't use a hood type light that fits directly on top of the tank.

Do a search on "UVB" for many other postings talking about it.

Yes, if you use the Search function, you will find many opinions. Most avid crabbers agree that a UVA/UVB light source is beneficial. I think they are becoming more popular to use.

I will do a search but i guess what confuses me is are they a luxury or a necessity.

That's a good question. I wouldn't say "luxury", but "beneficial" vs "necessity" is a good question.

I think we're all pretty confident it's beneficial. Crabs seem to be happier, it mimics natural environment better. But it's hard to say for sure that 'tis "necessary" without some more rigorous experiments.

My opinion, is it's not going to harm them in the short term if you don't. But after a couple years of crabbing, getting some UV lights should be one of the upgrades you make.

JediMasterThrash wrote:That's a good question. I wouldn't say "luxury", but "beneficial" vs "necessity" is a good question.

I think we're all pretty confident it's beneficial. Crabs seem to be happier, it mimics natural environment better. But it's hard to say for sure that 'tis "necessary" without some more rigorous experiments.

My opinion, is it's not going to harm them in the short term if you don't. But after a couple years of crabbing, getting some UV lights should be one of the upgrades you make.

Well said, indeed! I've noticed with my crabs that they are on a very good schedule with the light that I installed in the tank. They know when the night time comes and they know when to hide away.

I definitely agree that UVA/UVB light is beneficial.

One thing to keep in mind when using fluorescent lights is that even though the light continues to work, the amount of UVA/UVB rays being produced diminishes considerably after a year so it's a good idea to replace your bulb once a year.

Also, bulbs are not created equal so do some research to make sure you are purchasing lights that provide these rays.

im getting my new 55g tat set up and have glass aquarium lids and also hoods with both heat lights and fluorescent light. As you know the glass lids for aquariums aren't full lids, they have a space that runs the back of the tank that's open, is that sufficient for the UVB/UVA to get in the tank? The fluorescent bulb is in the back of the hood, over the opening (im almost positive of this). These hoods (i have 2 24" for my 55g) state "This fixture is for use over covered terrariums only." And on installation instructions it specifically states to place cover on first then the hood. The instructions also state "Plastic and glass terraium covers reduce UVB light output. But Im pretty sure the heat lights would warp or ruin plastic, so would the glass aquarium lid with the space in back be ok? I dont wanna bust the glass and I dont wanna provide UVB rays they aren't getting.

thanks in advance

glass will reduce the UVB transmission by 90-98%, which is why it's good to get an extra strong light (5.0 or 8.0) if you have a glass lid. UVA will penetrate. Plastic/plexiglass will only block about 40% of the light, and wire mess will block about 20%.

I have a 55 gallon and I use 2 glass lids for both sides of the tank. This is how I do it : On one side I use one reptile strip light (day and night) heat bulbs, and on the other side I have the glass lid folded back and the uva/uvb 2.0 florescent strip light fits down perfectly on the tank in front of where its folded back, so it is exposed and able to penetrate into the tank. I just make sure the crabs can't reach the bulbs in that area of the tank.

Thansk every one.. i was just a little confused on that one.


THANKS!