Hi,
Marine toads are very easy to care for as long as you provide them with enough space. They are very adaptable and have been introduced to many places.
A basic cage setup for one medium sized toad would be start with a 30 gallon aquarium. Coconut husk fiber would probably be the best substrate to use. You can buy it at pet stores under brand names like Bed-a-beast, Eco Earth and Forest Bed. If you can't find that a mixture of moist peat moss and sand or potting soil that is free of fertalizers and other chemicals would probably work fine. The only other things to put in the cage are a few places to hide like pieces of cork bark and drift wood as well as a large water dish for bathing. Only use dechlorinated tap water or bottled spring water.
Marine toads do best when kept in the high 70's during the day but they will tolerate a large range of temperatures. You might want to consider using a low wattage light bulb to heat one half of the cage to create a thermogradient for the toad.
As far as diet goes these toads are not picky. The one I cared for only measured about 5 inches but accepted crickets, hissing cockroaches and pinky mice. Pretty much any moving thing that can fit in its mouth will work. Some toads have even been trained to eat canned dog food but that is too high in fat to be the only thing fed to a toad. Most of their diet should be invertabrates like crickets, hissing roaches, lobster roaches and night crawlers but you can also try other interesting foods too. Here are two care sheets I found online:
http://freespace.virgin.net/darren.biggs/Caresheets/Amphibs/Cane_toad.html
http://www.jackspets.com/reptilehints/MARINE TOAD.htm
Good luck,
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Devin
devin@amphibiancare.com
www.amphibiancare.com