Compressed Coco Blocks Substrate Fungus?


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May 29, 2019
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Julian, CA
Has anyone had any problems with Coco fiber substrates and fungus or mold? I had a Rhino Rat snake die fairly suddenly after I put in some freshly expanded coco fiber from a compressed block. Of course it was very moist because of the water used to expand the block. Should we allow the coco fiber substrate to dry out first, or do you use it immediately in your enclosures or bins? I assumed that it was OK to use in it's moistened state because it is advertised as a good thing that the coco fiber substrate retains moisture well. Recently, I saw my Scrub Python with his nose pressed against the gap between two glass door panels as if he was seeking fresh air. I had just put in newly moistened coco fiber substrate and it had a pretty strong musty odor to it. I removed my snake immediately to a holding bin and am now drying the substrate in the sunshine outside. Is this stuff safe in its newly moistened state, or should it be dried out before use? I know this stuff may sit around for a while in warehouses before it is used.
It would depend on air circulation in the enclosure. I use it slightly damp but my building is very dry and it tends to dry out within hours. However, it it's staying wet for days, I'd let it dry before putting it in.
Coco fiber molds like nothing else. It is a crummy product. It retains moisture poorly, IME -- it gets sort of soggy when wet, gets moldy when moist, and goes from moist to dusty-dry too quickly. Not sure what you're after with "moisture retention", but I think a lot of keepers overthink and overvalue the substrate in this regard.

If you like the fine particulate substrate, something like Zilla's Jungle Mix works well (I switched to it after loosing two geckos on coco fiber -- ingestion/impaction, most likely). It is expensive, but so are animals, so take your pick.

For the species you mention, coco chips ("Repti-Chip", lots of other brands) would be an inexpensive option.

Keep in mind that coconuts are grown in regions that allow pesticides banned in the US and EU (carbofuran), and substrate products aren't subject to the same sorts of pesticide limits as imported food. If a person were especially worried about chemical contamination, a peat-based product would likely be the better choice.
I probably should have said compressed coco CHUNKS. What I have been using is the big, chunky stuff, not the fine fibers. I have several 6 ft enclosures with big snakes. The fine substrates would not work very well in these set-ups. What I like best is a cypress mulch that I usually get from Pet Kingdom in San Diego. It's their own product, but they are usually out of stock. I have been looking for alternatives. Has anybody been using the No Float brand of Cypress mulch?
I buy Prococo chips by the pallet and have been using it for 3 years now, with no issues.
It's all about how much water you use to break apart the block. I am currently the distributor of the CHIPPER for pa. The key is when breaking down ANY coco to add as minimal water as possible to break down the block. You can always add more water but to let it dry out is a pain in the butt. The CHIPPER sells COCO2GO which is a trpl washed coco tht has no fiber or dust & needs NO water to break down. You open the bag & use, simple as tht.
The most common mold I've seen from compressed coco fiber to date has been the yellowish flower pot fungus (Leucocoprinus birnbaumii). It is a known problem in nurseries as the mycelia can make it difficult for the media to absorb water.
Contrary to a number of claims, this fungus is ignored by isopods and springtails and the only real prevention is to sterilize the media before use.

Thanks everybody for all the good information. I don't want to call out any particular brands that I have had problems with. I know now that I probably used it too wet to start with. User error. But when you lose a snake suddenly, and you have suspicions as to the reason, you become wary to try the same product again. The latest brand I am trying is ReptiChip. I put it in wet and it smelled off immediately. I have since taken it all out of the enclosure and dried it in the sun and air. Now it seems like it will be fine. So I have decided NOT to give up on using coco chip blocks yet. I have also checked out the other brands/products suggested in this thread and will consider them in the future. Thank you all. Wayne