ah. you are wondering about the pulchritudinous namesake of the website? happy to explain.

Fundulus parvipinnis, the California killifish, is one of the giants of the marine realm. Not in stature, surely - they only get to be a maximum of 11.5cm, and even a 10 cm one is considered a monster. But this little fish is attractive, charming, hardy, and a serious player in the salt-marsh ecosystems of the Pacific coast.

Let’s start with the name. The genus “Fundulus” comes from the Latin fundus for “bottom”, as the first described species of this genus had a habit of burrowing into mud (Moyle 1976). The etymology of the common name “killifish” for members of the Cyprinodontidae is less clear, but may be a contraction of the words “killing fish”, since the word “killing” was used in colonial times for exceptionally effective bait (Moyle 1976). Common names for F. parvipinnis include Pacific killifish (Wells and Zobell 1934, Miller 1943), California mud-fish (Ritter and Bailey 1908), and most commonly, California killifish (Miller and Lea 1976). 

The California killifish is, as I mentioned, small, and spends his life in (or near) wetlands ranging from Morro Bay, CA all the way down to Bahía Almejas, Baja California Sur (Miller and Lea 1976). In many of these systems, the California kilifish is the numerical dominant of the fish world (sometimes representing as much as 80% of the ichthyofauna). The overall color is an enchanting olive green on the back and sides, with lighter yellowish brown on the underside. Males become darker on the back, and are brighter yellow laterally and on the underside. They develop scale ctenii when breeding, and are distinguished by much longer anal fins than females (Myers 1930).  Markings vary between populations.  Girard (1854) and Jordan and Evermann (1896) stated that females possess a dark dusky lateral band, while males possess olive-green bars laterally.  However, males, females, and juveniles of the population in Anaheim bay possess bars (Fritz 1975), and juvenile fishes taken from Laguna Ojo de Liebre (BCS, Mexico) also possess distinct bars (Talley 2000).

They start their short (12-18 month) lives as tiny juveniles - only 7 or 8 mm long, sticking to the high marsh habitats, particularly small intertidal pools and creeks (Fritz 1975). These habitats can be difficult - salinity can go as high as 70 psu or more (personal observation), and temperatures as high as 40°C. Numerous studies (see Talley 2000 and references there) have shown a phenomenal range of tolerances for variation in salinity and temperature - California killifish have been shown to reproduce in salinities from fully fresh to 60, and surviving in ridiculously hypersaline waters (128 PSU). Still, for a little fish like this, dealing with those conditions seems to beat the danger of facing the larger predators in deeper waters.

The rest of their lives, killifish make tidal migrations….that is, when the tide comes in, they venture out of the pools into the vegetated marsh, where they can feed on insects, amphipods, etc. that would be unavailable during lower tides. Then as the tides recede, they return to their pools as a refuge. As killifish mature, they increase the distance for their excursions, moving farther up the marsh and farther down into the creeks. Broadly, the larger the killifish, the deeper the water they prefer (Fritz 1976, Talley 2000).

On a larger scale, California killifish seem to move very little between marshes. Bernardi and Talley (2000) found high levels of genetic differentiation between populations of California killifish along the coast of Alta and Baja California, and inferred low dispersal between marshes.  A low level of genetic exchange is consistent with the reproductive behavior (see below) and large size at hatching (Watson 1992) of F. parvipinnis, and with the observation that California killifish are rarely found along the open coast as larvae or adults (Watson 1992), even immediately offshore of a large estuary (Nordby 1982). 

There have been a few studies of foraging patterns in F. parvipinnis, and while they differ in details, the broad finding is that crustaceans make up a large proportion of their gut content, but they also consume polychaetes, insects, and small molluscs. Since killifish in turn are an important food resource for piscivorous fishes and birds, this gives them a fairly central location in the food web. And the total amount of energy moving through Fundulus is amazing - for example, Pérez-España et al. estimate that each year 1,930 tons of biomass (mostly microcrustaceans) is consumed and 187 tons of biomass produced (~10% transfer efficiency) by F. parvipinnis in the Ojo de Liebre lagoon. 

Fundulus parvipinnis spawns on spring high tides, in *very* shallow waters, possibly to allow access to the high intertidal pools, where eggs would experience relatively warm water temperatures and lowered risk of advection (they do, after all, want to stay on the marsh!). Further, food resources for larval fish may be replenished by the tides (Kneib 1993), therefore synchronizing spawning such that larvae hatch during spring tides and maximum inundation of upper marsh would promote growth. These advantages favor spawning during April-June, which Fritz (1975) considered the peak season.

 From April through September along the range of F. parvipinnis distribution, spring high tides occur at night.  Additionally, the spring is a period during which water temperatures generally are rising (e.g., see West and Zedler 2000), it is also a period of minimum daytime inundation for high intertidal habitats.  This low inundation time during daylight means the intertidal pools will be isolated and under insolation for long periods, allowing them to warm and become hypersaline (Lennon 1995, Talley 2000).  As warm temperature and high salinity promote rapid hatching and growth for killifish eggs and larvae, spawning in April through June (the reported peak spawning periods in Fritz 1975) would be another selective advantage. Finally, it should be mentioned that densities of temperate, soft-bottom macrofauna, which are common prey items for F. parvipinnis, tend to peak during the Spring and Fall (L. Levin personal communication), and this may provide greater nutrition, promoting egg and sperm production.

So, what more could you ask for? An abundant, attractive, and hardy local fish; an interesting life history; an integral part of the food web for an ecosystem that is highly threatened….the California killifish has it all.

And now it has its own website

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REFERENCES

Bernardi G, Talley D. 2000. Genetic evidence for limited dispersal in the coastal California killifish, Fundulus parvipinnis. Journal of Experimental Marine Biology and Ecology 255: 187-199.

Girard C. 1854. Observations upon a collection of fishes made on the Pacific coast of the United States by Lieut. W.P. Trowbridge, U.S.A, for the Museum of the Smithsonion Institution. Phila. Acad. Nat. Sci., Proc. 7: 142-157.

Kneib RT. 1993. Growth and Mortality in Successive Cohorts of Fish Larvae Within an Estuarine Nursery. Marine Ecology Progress Series 94: 115-127.

Miller RR. 1943. Further data on freshwater populations of the Pacific killifish, Fundulus parvipinnis. COPEIA 1: 51-52.

Moyle PB. 1976. Inland Fishes of California. Bekeley: University of California Press.

Myers GS. 1930. The killifish of San Ignacio and the stickleback of San Ramon, Lower California. Proceedings of the National Academy of Sciences XIX: 95-104.

Perez-Espana H, Galvan-Magana F, Abitia-Cardenas LA. 1998. Growth, consumption and productivity of the California killifish in Ojo de Liebre Lagoon, Mexico. Journal of Fish Biology 52: 1068-1077.

Ritter WE, Bailey SE. 1908. On the weight of developing eggs. University of California Publication in Zoology 6: 1-10.

Talley DM. 2000. The Role of Resident Fishes in Linking Habitats of a Southern California Salt Marsh. University of California, San Diego, La Jolla, CA.

Watson W. 1992. Cyprinodontidae in Moser HG, ed. The early stages of fishes in the California Current region, vol. Atlas 33 California Cooperative Fisheries Institute (Cal.C.O.F.I.).

West JM, Zedler JB. 2000. Marsh-creek connectivity: Fish use of a tidal salt marsh in southern California. Estuaries 23: 699-710.