Killifish breeders have used peat moss for years. German fibrous peat has long been recognized as the "best" peat. This peat tends to be resemble something like a mat of tree roots. The loose, open consistency allows fish to easily penetrate the material to either spawn or hide.
In the United States, the primary source of peat moss has been Canadian sphagnum. Recently, concerns over the permanent loss of peat bogs has led aquarists to more fervently seek substitutes. American peat differs from fibrous peat in that it is granular rather than stringy. It is still light enough that killies can dive into it, but it tends to be messier and less attractive to view than fibrous peat.
Bill Gallagher, of the Bay Area Killifish Association, introduced the use of coconut fiber as a peat spawn substitute in 1999. Coconut fiber is a leftover material in the coconut harvesting process. It actually resembles Canadian sphagnum more than German peat fibers. Coconut fiber is a less active element than peat moss. It does not discolor or acidify the water as rapidly or to the degree that peat does. This can be an advantage in a variety of set-ups, particularly with species preferring neutral or alkaline water conditions. So far, the only drawbacks to coconut fiber are: 1) it does not acidify water like peat does, and 2) it is reported to be less effective for storing killie eggs during a "drying" stage. Some hobbyists use a mixture of peat and coconut fiber when storing eggs. Coconut fiber can be very useful in the aquarium and can serve as a peat substitute.
Bill Gallagher has been experimenting with another peat moss substitute. This one has many of the characteristics of German peat fiber. It is shredded redwood bark. Like coconut fiber, redwood fibers are chemically less active than peat moss. Redwood fibers are not as flexible (soft) as German peat fibers, but it is very difficult to discern much difference in appearance. Killies like the redwood fibers as both a spawning site and a hiding place.
Shredded redwood bark is readily prepared for use. Just place it in a bucket of water and let it saturate. No boiling (and the accompanying mess) is required. Pull out what you need when you need it. It is a good idea to drain and replace the water in the bucket weekly.
Most non-annual killie eggs take a minimum of 14 days to hatch. To use redwood fibers as a spawning material you have two options. First, you can move just the adult spawners to a new container every two weeks and just wait for fry to appear. The second choice is to move the redwood fibers. Pull out the redwood clumps and put them into another container (Bill Gallagher uses clear margarine tubs), then siphon the remainder of the redwood into a pail, let the flush water settle in the pail, then siphon off the bottom wash with the remaining little redwood fines into the margarine tub. Then label the tub and wait up to 30 days (fry will appear even after 30 days).
If you want to work, then check the clear margarine tub daily with flashlight, and suck the fry out with small baster or eyedropper. A truly lazy method is after you start seeing fry appear, just sink the margarine tub into your first grow-out container (large flat shoe box, 10-gallon tank, whatever) and just have them move out into the water by themselves.
A margarine tub stuffed with this stuff in water will get a little anaerobic after awhile, so it is recommended that you use larger or flatter containers, make frequent, small water changes, and/or maybe add an air-stone (I haven't tried that, but it should do the trick). Peat moss and coconut fiber can also rot and create an anaerobic condition as you might use the techniques with them also..
To prevent anaerobic bacteria in the redwood, Bill Gallagher has experimented with storing the "dry" redwood with eggs in ziploc bags and storing it like annuals. It stays moist and does not actually dry out this way. He waits 3 weeks and then wets the redwood. He has had some luck this way, but not as much as the wet method. He is hoping to perfect this method as it would seem to be identical to the "put the eggs on peat" method that results in the uniform hatches, instead of the drawn out hatches in water.
Where can you find shredded redwood bark? A search of garden stores and large stores in the Phoenix area did not turn up any retailers that were offering shredded redwood bark until we checked out Lowe’s, a large national home improvement chain that was opening stores in the Phoenix area. We discovered Bandini brand shredded redwood bark. It is now available in Arizona, and possibly is found throughout the United States. Try it, you might like it!