I'm a postdoc interested in finding locations in the US where zebra danio (danio rerio) is living in the wild such as streams, ponds, lakes, road-side ditch, etc... I realize they are not indigenous to the US, but I'm assuming that there have been enough accidental/aquarium releases over the past few decades that there should be some sites in the southern states were they've been established for a couple of years. I doubt any of you are actively collecting zebra danio, but I figure that folks on this site may have run across them while collecting other fish. I'm located near SF Bay in CA so that is most interesting to me, but locations as far as FL would be interesting too. I'm new to the field so any information would be appreciated. Thanks.

Edited by jfb, 02 February 2012 - 03:32 PM.

Are you familiar with the USGS Nonindigenous Aquatic Species database? It has a few hits for zebra danios, none terribly recent.

http://nas.er.usgs.gov/

...I'm assuming that there have been enough accidental/aquarium releases over the past few decades that there should be some sites in the southern states were they've been established for a couple of years....

Have you seen this?

The American Midland Naturalist 160(2):477-479. 2008
doi: http://dx.doi.org/10.../0003-0031(2008)160[477:FCOLLT]2.0.CO;2
Field Confirmation of Laboratory-Determined Lower Temperature Tolerance of Transgenic and Wildtype Zebra Danios, Danio Rerio
Cheryl Cortemeglia, Thomas L. Beitinger, James H. Kennedy, and Tammie Walters
Department of Biological Sciences, University of North Texas, P.O. Box 5218, Denton 76201

ABSTRACT
A transgenic variety (red glofish) of the aquarium fish, zebra danio (Danio rerio) and wildtype zebra danios were exposed to the natural climate of north Texas in four, outside, 10,000-L microcosms during the winter of 2004–2005. At least 13 of 68 fish survived at temperatures as low as 7.5 C; however, none survived a 4 d exposure to 4 C following a cold front. These field results corroborate laboratory findings that the lowest temperature that these two varieties of D. rerio can survive is about 5 C.

Here's a website that will give you the average and maximum recorded low temperatures for various cities, like Miami: http://www.weather.c.../graph/USFL0316
The average low temperatures are in the 60's, but the record lows are below the 41 degree Fahrenheit cutoff that the above paper says is the lowest tolerance temperature for Danio rerio survival. It is therefore unlikely that Danio rerio is capable of surviving its first winter after being released. The usgs website that Decal linked to above lists the fish as being "Failed/Extirpated/Eradicated". Link: http://nas2.er.usgs....x?SpeciesID=505

Edited by EricaWieser, 02 February 2012 - 09:19 PM.

Even with the record lows being what they are, I still suspect they could be established in South Florida or Texas, not to mention isolated populations in thermal refuges throughout the country. Miami-Dade and Broward Co. have some ridiculous introduced spp. swimming and crawling about... I've seen pictures of chameleons on the herp side. Here in Houston plecos thrive despite regular winter die offs.

Are you familiar with the USGS Nonindigenous Aquatic Species database? It has a few hits for zebra danios, none terribly recent.

http://nas.er.usgs.gov/

Thanks for reply. Yes, I had stumbled upon some of their data, but I didn't have the main site, so thanks. You're right, though, that most of it seems pretty dated.

No, I had seen that paper, thanks. There's probably some good references in it too. I'd have thought they were more hearty since they are native to the Himalayans, but apparently not.

Have you seen this?

The American Midland Naturalist 160(2):477-479. 2008
doi: http://dx.doi.org/10.../0003-0031(2008)160[477:FCOLLT]2.0.CO;2
Field Confirmation of Laboratory-Determined Lower Temperature Tolerance of Transgenic and Wildtype Zebra Danios, Danio Rerio
Cheryl Cortemeglia, Thomas L. Beitinger, James H. Kennedy, and Tammie Walters
Department of Biological Sciences, University of North Texas, P.O. Box 5218, Denton 76201

Here's a website that will give you the average and maximum recorded low temperatures for various cities, like Miami: http://www.weather.c.../graph/USFL0316
The average low temperatures are in the 60's, but the record lows are below the 41 degree Fahrenheit cutoff that the above paper says is the lowest tolerance temperature for Danio rerio survival. It is therefore unlikely that Danio rerio is capable of surviving its first winter after being released. The usgs website that Decal linked to above lists the fish as being "Failed/Extirpated/Eradicated". Link: http://nas2.er.usgs....x?SpeciesID=505

Interesting. I've heard that the hobby of some folks is maintaining outdoor ponds filled with exotic plants and fish. I wonder if they start over each year. Probably this isn't the best forum for such a question though...

Even with the record lows being what they are, I still suspect they could be established in South Florida or Texas, not to mention isolated populations in thermal refuges throughout the country. Miami-Dade and Broward Co. have some ridiculous introduced spp. swimming and crawling about... I've seen pictures of chameleons on the herp side. Here in Houston plecos thrive despite regular winter die offs.

Max and min air temps are not a good predictor of water temps. Groundwater seepage can create warm pockets in winter and cool pockets in summer where fish can wait out the lethal extremes. Your thermometer may read 5C at the stream surface, but there may be small refugia (under banks, rocks, etc) that are 10 to 15 C due to groundwater.

Interesting. it seems like that could be an important effect.

Max and min air temps are not a good predictor of water temps. Groundwater seepage can create warm pockets in winter and cool pockets in summer where fish can wait out the lethal extremes. Your thermometer may read 5C at the stream surface, but there may be small refugia (under banks, rocks, etc) that are 10 to 15 C due to groundwater.

Many rivers in Texas, have areas of spring-water inflows that create a temperature stable, year round oasis.
An extreme example, the Comal River in New Braunfels TX, is entirely spring fed. Or, more precisely, it is an underground river that emerges suddenly a before its confluence 2.5 miles later with the Guadalupe. The river's water temp does not vary more than a degree or two, up or down, from 72°f (summer or winter). It's a wonderful place to snorkel. Danios? No.

There are many "tropical oasis" warm springs throughout the west that, unfortunately, have introduced tropical fish. Several in Utah are salt water and contain reef fish sp. The owner of Bonneville Seabase tried to recreate a reef environment for year round diving. Kudos to him for cleaning out what had become a dump site. However, after stocking with "rescue fish", he succeeded primarily in re-creating a gigantic, overstocked, out-of-balance and unfiltered saltwater aquarium, complete with poor visibility (4-5 feet is common).

Rick

Edited by rickwrench, 03 February 2012 - 02:12 PM.

Thanks, Rick. I hadn't thought about the influence of spring water. The Bonnefille Seabase sounds intriguing but probalby no danios there either. Finding wild danios is turning out to be harder than I expected, although that's probably a good thing since they are invasive...

Many rivers in Texas, have areas of spring-water inflows that create a temperature stable, year round oasis.
An extreme example, the Comal River in New Braunfels TX, is entirely spring fed. Or, more precisely, it is an underground river that emerges suddenly a before its confluence 2.5 miles later with the Guadalupe. The river's water temp does not vary more than a degree or two, up or down, from 72°f (summer or winter). It's a wonderful place to snorkel. Danios? No.

There are many "tropical oasis" warm springs throughout the west that, unfortunately, have introduced tropical fish. Several in Utah are salt water and contain reef fish sp. The owner of Bonneville Seabase tried to recreate a reef environment for year round diving. Kudos to him for cleaning out what had become a dump site. However, after stocking with "rescue fish", he succeeded primarily in re-creating a gigantic, overstocked, out-of-balance and unfiltered saltwater aquarium, complete with poor visibility (4-5 feet is common).

Rick