Low Temperatures and Cyprinodonts.

By Martin R. Tversted - Denmark

More and more people around the world have started keeping their Goodeids with a cool winter rest as a base for a good breeding. For many this seems revolutionary, to keep toothcarps at these low temperatures. However, there are many species from this family, cyprinodontiformes, that can handle these low temperatures. Yes, many do directly benefit from low temperatures for a period during the winter months.

For the species mentioned in this article the cool temperature can vary from one month to five months – all depending on the species.

I have for some of them indicated that they are cold-hardy in the Danish climate (winter down to –23C), as they are hardy in a garden pond. However, some of them are only marginally hardy. They can handle the low temperatures but not the winter rain which can cause the water to become acidious. Others can handle the cold temperatures but not the length of them.

This article does not cover how to make a succesful garden pond for toothcarps.

Most species in this overview can be used as garden pond fish during the summer months and this can give the hobby a new aspect as well as teach us something about their natural behaviour.

All the here given data should be considered as a guideline. It can all ways be recommended to investigate the species naturel history as well as the climatic data from their habitat.

An incompleate overview above these species with lowest temperature reference are:

Goodeids:

Allodontichthys tamazulae 12C*

Ameca splendens 10C*

Ataeniobius toweri 10-15C*

Allotoca dugesii 10C*

Allotoca catarinae 10C*

Allotoca maculatus 10C*

Allotoca meeki 10C*

Alloophorus robustus 10C*

Chapalichthys pardalis 12C*

Girardinichthys viviparus 7C*

Goodea atripinnis ssp. 10C*

Hubsinia turneri 10C*

Skiffia multipunctatus 7C*

Xenoophorus sp. Illescas 7C*

Xenotoca eiseni 10C*

Xenotoca eiseni “San Marcus” 10C*

Xenotoca melanosoma 10C*

Xenotoca variata 12C*

Zoogoneticus tequila 12C*

Other livebearers:

Cnesterodon species from Uruguay and Argentina 4C

Gambusia affinis 7C

Gambusia holbrooki 4C

Jenynsia lineata 4-10C

Jenynsia multidentata 4C*

Poecilia latipinna (forms from the Carolina states and Texas) 4C*

Poecilia latipinna (forms from other northamerican states) 10C*

Poecilia mexicana 4-10C (Depending on location)

Poecilia sphenops (Liberty Molly) 14C*

Poeciliopsis infans 4-10C

Heterandria formosa 10C*

Phalloceros caudimaculatus (southern forms from Uruguay and Argentina) 4C

Phalloceros caudimaculatus reticulatus 10C*

Xiphophorus evelynae 10C*

Xiphophorus helleri (green aquarium form) 10C*

Xiphophorus nezahualcoyotel 7C*

Xiphophorus maculatus (Blue Mickey Mouse Platy) 10C*

Xiphophorus malinche 10-15C

Xiphophorus variatus 7C*

Annual killiefish:

The Austrolebias-genus 4C*

Simpsonichthys constanciae 14C*

The Megalebias-genus 4C*

Nematolebias whitei 10C*

North and Central American Killiefish:

Fundulus catenatus 4C

Fundulus chrysotus 14C

Fundulus confluentus 14C*

Fundulus diaphanus ssp. 4C (hardy in Denmark)

Fundulus dispar 4C

Fundulus heteroclitus 4-10C

Fundulus nottatus 4C(Hardy in Denmark) *

Fundulus zebrinus 4C (Hardy in Denmark)*

Fundulus sciadicus 4C (Hardy in Denmark)

Crenichthys baileyi baileyi (7C night temperature)12C*

Cyprinodon eremus 10C*

Cyprinodon nevadensis nevadensis 10C*

Cyprinodon variegatus ovinus 4C (Marginally hardy in Denmark, depending on good water quality)*

Jordanella floridae (7C night temperature)12C*

Lucania goodei 10C*

Lucania parva 4-12C (depending on the  population)*

European and Middleeastern killifish:

The Aphanius anatoliae group with subspecies 2C (Marginally hardy in Denmark, depending on good water quality)*

Aphanius apodus 10C*

Aphanius danfordii 0C (Marginally hardy in Denmark, depending on good water quality)*

Aphanius dispar 4-15C (depending of the origin of the fish)*

Aphanius iberus 4C (Marginally hardy in Denmark, depending on good water quality)*

Aphanius mento 4-10C*

Aphanius sirhani 10C*

Aphanius sophiae 4C*

Valencia hispanica 4C

Valencia letourneuxi 4C*

The here given data are based on own experience (marked with a *), experience from others or habitat informations.

You are all ways welcome to write me an email for more informations.

Martin Tversted

emys@email.dk