This pretty little non-native water fern species can be found in very wet ditches, canals, and pondsides across central and southern Florida. I was surprised to see that it is not a listed invasive species here in Florida as it is spreading quite rampantly along some canals in my area. Although it has been eaten both raw and cooked in parts of Asia and Africa, I warn against consuming it. One unconfirmed warning states that it contains harmful "carcinogenic chemicals." Please let me know if you know of anyone in other countries who consume this particular species. It is also used as a green manure, water clarifier [helps remove algae, etc.], in biological research due to its short lifespan, and as a somewhat popular aquarium plant. The other Ceraptopteris species found in Florida, the native C. pteridoides, "is nearly always floating." C. thalictroides is "rooted in wet soil or on the bottom in shallow water." Note that, according to fern experts R.M. Tyron and A.F Tyron, "the species taxonomy of Ceratopteris is exceptionally difficult. The occurrence of morphological intermediates, including putative hybrids, complicates the delimitation of species." Alrighty-then.
CAUTION: DO NOT CONSUME - Although cooked and eaten in the Malagasy Republic [Madagascar], Vietnam, and probably elsewhere, it Is “believed to contain carcinogenic chemicals.” [5, “citation needed”] THIAMINASE WARNING: "Many ferns [and possibly this species] also contain thiaminase, an enzyme that robs the body of its vitamin B complex. NOTE: Some websites state that thiaminase should be deactivated by cooking or drying, but I must do more research to confirm this fact.
EDIBILITY: SEE CAUTION ABOVE – DO NOT CONSUME. “Fronds are cooked and eaten as a vegetable in Madagascar  , New Guinea , and Vietnam , and raw as a salad in Micronesia [citation needed.” Edible.  “The plant is often used as a vegetable, especially in Asia, and is sometimes grown on a garden scale for this purpose. The young leaves, before they have uncurled, make excellent greens and when cooked or blanched they can be eaten as a salad. In some parts of Asia it is an established luxury vegetable.” [12, via 11] Plant Resources of Tropical Africa. It is not mentioned on eattheweeds.com.
MEDICINAL USES: It is simply listed as medicinal on (Manickam and Irudayaraj 1992). [9, 10] “Rhizomes and fronds are used as medicine for foetal toxins and accumulation of phlegm.” [15, via 11] “Both the leaves and the root are used as a poultice against skin complaints, e.g. as a drawing agent on carbuncles.” [12, via 11] “In China they are used as a styptic to stop bleeding.” 
CHEMICAL CONSTITUENTS: “Alkaloids, arbutin and tannin have been found in the green parts of the plant.” [12, via 11]
WILDLIFE: Although non-native, “it can provide useful shade to shyer fish and small fry.” 
GREEN MANURE: “The plants can be used as a green manure in rice fields.” [12, via 11, and 10]
CLASSIFICATION: “The dense roots are said to take nutrients out of the water helping to prevent the growth of algae.” 
BIOLOGICAL RESEARCH: “Ceratopteris thalictroides and especially also Ceratopteris richardii, serve as model plants in developmental biology and molecular research. They are useful for research because they have independent haploid and diploid life phases, a short life cycle, a simple genetic system, and reproduce by single-celled haploid spores.” [15, via 11] Flora of China
AQUARIUM PLANT: Some Ceratopteris species are “popular aquarium plants.”  including the two that grow wild here in Florida.  This species “helps prevent algae by consuming large amounts of nutrients.” 
CLASSIFICATION: It is classified in the subfamily Ceratopteridoideae. 
NATIVE TO: Asia, Africa, etc. To see a long, complete list of countries that it is native to, go to iucnredlist.org.  Not native in Florida, where it grows wild from near Orlando southwards, in many scattered counties. 
HABITAT: They “may be found floating or rooted in the mud.”  “Plants usually rooted in mud.”  Canals, wet ditches. In “still, sluggish waters.”  Also ponds.
- ANNUAL: “Swamp fern has a very short life cycle. The whole cycle from spore to spore can be completed in less than 30 days.” [14, via 11]
- HEIGHT: 18-30"+. 
- RATE OF GROWTH: Usually rapid. 
- LEAVES: Forms are “highly variable. There can be several types and shapes on one plant, some immersed and some floating.”  “The floating leaves are often thick and fleshy, with dep lobes on the margins.”  Also finely divided.
- FERTILE LEAVES/FRONDS: “The curly [frilly] leaves are the reproductive leaves.”  “Ball-shaped [spore-producing] sporangia on some of the undersides” of the leaves. 
- LIGHT: “It grows best in very high amounts of light.”  “Full sun to moderate shade.”  Medium. 
- pH: 5-6.5 [13, via 11] The New RHS Dictionary of Gardening, 1992]
- PROPAGATION: “Small adventitious plantlets.” 
RELATED SPECIES: One other Ceratopteris species grows wild in Florida, the native C. pteridoides, aka WATER HORN FERN or FLOATING ANTLER FERN. [1,2] It is found in parts of South and Central America, the Caribbean, Georgia, Louisiana, and in Florida it grows from near Gainesville southwards in scattered counties. 
- "Flora of North America Editorial Committee (1993) has illustrations of both C. pteridoides and C. thalictroides." 
- Ferns and Allied Plants writes, "C. pterioides, with inflated petioles, is nearly always floating, while C. thalictroides is rooted in wet soil or on the bottom in shallow water." 
- There are six species of Ceratopteris worldwide. 
Wet Ditches, Canals
Rate of GrowthFast
Sources for acquiring
Not readily available from nurseries... grows wild in central and southern Florida.
I suggest NOT purchasing or planting this non-native species as I see it spreading in wet ditches and canals here in Florida.
 IFAS – Center for Aquatic and Invasive Plants [page and attached video] [https://plants.ifas.ufl.edu/plant-directory/ceratopteris-thalictroides/]
 Atlas of Florida Plants
 USDA Plants database
 Flora of North America [efloras.org]
 tropica.com [Tropica Aquarium Plants]
 Plant Resources of Tropical Africa 2: Vegetables
 Edible Wild Plants of Vietnam
 iucnredlist.org [IUCN Red List of Threatened Species]
 Manickam and Irudayaraj, 1992 [via 9]
 tropical.theferns.info [Useful Tropical Plants]
[12, via 11] Plant Resources of Tropical Africa
[13, via 11] Discovering Wild Plants – Alaska...
[14, via 11] Protabase - Plant Resources of Tropical Africa
[15, via 11] Flora of China
[16, via 11] The New RHS Dictionary of Gardening, 1992]
 Regional Conservation
 Ferns and Allied Plants: With Special Reference to Tropical America