Cyprinodontiformes vivíparos e ovovivíparos

Livebearer Cyprinodontiformes

Artigos - Resultado da prospecção ao lago em Fevereiro de 2009

Articles - The February 2009 fish pond assessment

















The February 2009 fish pond assessment

Miguel Andrade - published at this website in May 2009

Climate anomaly or climate cycles ?
The final results from the fish pond assessment




In order to support my strongest believes that outdoors facilities ( fishponds ) are no doubt the most ethical, suitable, constructive and efficient method of captivity fish keeping, as a rule I am pretty aware about any piece of information that can confirm it.
In 2006, no more than a year after acquire my first Skiffia multipunctata group, I had the opportunity to read a remarkable scientific paper – “ The influence of rearing experience on the behaviour of an endangered Mexican fish, Skiffia multipunctata ”.

The abstract of this article is clear enough - “ reintroduction projects may fail because captive-reared animals do not possess the behavioural skills required for survival in the wild.
Rearing captive-bred animals in semi-natural enclosures prior to release has been used to improve the survival of reintroduced endangered species, but it is unclear how rearing environment influences the development of behaviour.
This study examined the effect of rearing conditions on the behaviour of the goodeid Skiffia multipunctata, an endangered species of Mexican fish.
Under standard laboratory conditions, the courtship, aggression, boldness and foraging behaviour of fish raised in aquaria was compared to that of fish reared in outdoor ponds.
We present initial behavioural descriptions for this species and show that laboratory-reared fish displayed increased courtship, aggression and curiosity towards a novel predator in comparison to their pond-reared counterparts.
Laboratory-reared fish also commenced foraging on a novel food item ( Artemia ) more rapidly than fish reared outdoors.
These findings suggest that captive rearing environments promote the development of behavioural tendencies, such as boldness and aggression, which could be detrimental to the survival of reintroduced individuals “, ( Kelley et al., 2005 ).

Most of common garden fish ponds are unquestionably bigger than any indoors tank and, off course, can contain larger water storage capacity and room by that reason.

Besides space, a aforementioned excellent argument, there are also a few other excellent points of view to take in consideration, like the benefits of sun light, ecological conditions as well as... all we need, to recreate, at our own home, any natural habitat, better than in whichever other confinement setup.


Figure 1 - This picture shows the fishpond one day before the intervention ( February 22nd 2009 ).

For climacterically reasons, sometimes our local weather conditions are quite far from the original, with reference to most species. As a rule for alien ( exotic ) fish species, standing outdoors for longer than certain precise periods of the year can represent a risk, either due to high temperatures during the hot peeks or, most commonly and frequently, by cold narcosis during winter colder months.
The live bearing Goodeids ( also known as splitfins ) are an interesting group of around 40 species native to west-central Mexico’s highlands. Some of them had become very promising outdoors species regarding our local climate ( take a look at the article
Goodeids, Some Promising Garden Fishpond Viviparous Fish as well ) .
Because we are talking about a number of endangered fish, some of them extinct already in nature, it would not be very ethical neither deontological to loose several individuals in some cold tolerance assessment experiment, more than ever when it is almost impossible to get access to numerous species.
My keeping efforts towards 5 of these species had in mid a special concern with maintaining a considerable wintering group, collected in the beginning of every fall.
Most of the species were released in fishponds again from April to October and collected once more, after this period, to indoors tanks, in order to assure the survival of a generous breeding stock.
In 2005 it was finally possible to let a small number of adults outdoors even at the critical period between October and March.
My communities of the only two species available in our local pet fish market,
Ameca splendens and Xenotoca eiseni had grown in to a considerable large number of effectives. The wintering tanks had no more adequate room to keep so many exemplars.
Their number was already so significant that some have even managed to escape from netting attempts and remain outdoors in that winter for the first time.
By the end of 2007, I was regrettably forced to give up a considerable section of my fish keeping conditions, for the second time in my live.
From that moment on it would be impossible to maintain for longer my indoors tanks and it was imperative to decide which species ( and Goodeids in particular ) it would be reasonable to continue with, due to this sudden unavoidably shortage of room.
In face of such an hard decision, my natural impulse was to resign ( and distribute freely among other hobbyists ) the most endangered or rare species, continuing to keep no more than two Goodeids; the above mentioned relatively common ones.
Until this last winter ( 2008-2009 ) the experience of rearing all year round Goodeids at a fish pond was running very well. Both species could hardly surpass the winter with an insignificant lost of older or fragile Ameca splendens on longer freezing episodes.
Since the starting point of this trial I had the conscience that some of our winters would reveal to be fatal to the outdoors groups.
Last October 2008 it was not achievable to capture more than a very small number of little fry from both species for the wintering backup group placed at the remaining last tank.
For crucial impeditive reasons, the fishpond was not drained out in fall for the first time in years.
In January 2009, an abnormal frozen episode it was responsible for the lost of one of the species kept in open air, Ameca splendens, and while the other, Xenotoca eiseni had proven to surpass unimaginable cold resistance limits.
This survival group had become a splendid revelation.
On the next lines some conjectures and details about this experiment will be exposed, along the most important facts about the climate in Portugal.
I hope to catch the attention of many fish keepers to the remarkable livebearer Goodeids as possible choices for our outdoors fish ponds, specially for the Atlantic Macaronesian archipelagos of Azores and Madeira, as well as a few species significant for main land Portugal, with particular attention to species like Xenotoca eiseni, which have conquer some hostility among community tank devotees.

Climate anomaly or climate cycles ?


When we carefully study the potential of or local climate with the intention of preserving exotic species captive populations in outdoors environments, it’s necessary to take into account that the weather is a very unpredictable and dynamic reality. 

Climate cycles and anomalies should ever be considered as well.

This is more significant when you don’t want to cause innocent lives lost or suffering to fish.

I confess that my experience with these species in semi-natural environment all year round is recent and my knowledge about this issue is still short and modest, but the intention to avoid predictable lost of fish by cold was always present.

The first group left outdoors in permanence had begun only in October 2005; therefore due to some unusual weather irregularities during this period of time, the issue on climate anomaly on this acknowledgment is so important.

That’s why the late fishpond assessment procedure, completed last February 2009 and described further, was imperative in face of the atypical frosty conditions that took place in the beginning of January 2009.

Another climate anomaly is presently taking place, not only for the warm end of this winter season but as well as for the drought circumstances in March.

We had 202,3 mm of rain fall in January, but only 75,9 mm in February and, some hard to believe, no more than 5,6 mm in March, with remarkable effects in maximum daily temperatures increasing due to the lack of clouds and the fresh breezes that come with the expected seasonal rainfall.

« March monthly accumulated precipitation in the central and western regions of the Iberian Peninsula presents a clear continuous decline of 50% during the 1960–97 period.

However, this is merely the most visible aspect of a larger phenomenon over the North Atlantic/European sector. The European precipitation trends in March for the period 1960–2000 show a clear distribution of increasing precipitation in the northern regions ( the British Isles and parts of Scandinavia ) together with decreasing trends throughout the western Mediterranean Basin », ( Paredes et al. 2006 ).

« The widespread declines of March precipitation in Iberia, and the consistent negative precipitation trends, predicted by most climate change scenarios, increase the concern about a possible future scenario with scarce water resources.

It is within this context that the detected decrease of precipitation in March can be indicative of  “ things to come ”, that is, lack of precipitation and water when it is most needed for spring plant growth as well as for human consumption during spring and summer seasons », ( Pereira et al. 2002 apud Paredes et al. 2006 ).

« If the average of March precipitation is kept within the present range of values and summer droughts become the norm, it is not difficult to foresee increasing water resources problems, including those of a transnational nature between Portugal and Spain », ( Vlachos and Correia 1999 apud Paredes et al. 2006 ).

Occasional abnormal conditions are not definitely substance for a climate change classification, but the prevalence of unusual tendencies in long-term, may be regarded as a significant change in the expected patterns of average weather of a specific region.

The climate change terminology reflects abnormal variations to the expected regional climate, according to the available data about a particular region precedent.

On the January 29th, 2006, something extraordinary took place when we had a snowfall event in areas where typically it is very improbable that could happen.

The intensity of this rare phenomenon wasn’t severe on this particular occasion, and most of the snow traces soon disappeared in a matter of minutes or hours. The last time it had happen previously in Lisbon it was in 1954.

On the January 28th 2007, some snowfall in several unusual regions had surprise again for the rarity of the phenomena, although it was the 2nd consecutive winter.

2007 was also another drought example on the recent years.

The total amount of rainfall was so glaringly small, that it was considered the second driest year since 1931.

Nonetheless, the standard draw season that take place in summer it was characterized for high quantities of precipitation, a situation completely out of the expected patterns of rainfall.

For this reason, the temperatures in June, July and August were lower than the usual, so the summer of 2007 was the coldest in no less than two decades.

The year 2008 was characterized by average values of maximum temperature, average temperature and minimum temperature slightly below the average of the 1971-2000 reference period, in - 0.1ºC ( -0.18ºF ), - 0.4°C ( -0.72ºF ) and - 0.2°C ( -0.36ºF ) respectively.

Also the figures of precipitation were below the average for the 1971-2000 reference periods, described as very dry to dry.

Thus, 2008 was the 8th driest year since the start of records in 1931, but on this same period the year 2005 was the driest.

The year 2008 ended with dry weather.

November 2008 was characterized by unpleasantly cold air temperatures. The value of the average minimum temperature, 4.7ºC ( 40.4ºF ), it was the third lowest value since 1931, with an abnormality of – 3.2ºC ( -5.7ºF ) below the 1971-2000 reference. The previous lowest values were 4.3ºC ( 39.7ºF ) in 1956 and 4,6ºC ( 40.2ºF ) in 1971.

December 2008, was characterized by average values of air temperature below the normal values for the 1971-2000 reference, and the average and maximum average temperature of the air less than 1.4ºC ( 2.5ºF ) compared to their average values and the average minimum temperature of less than 1.7ºC ( 3ºF ).

In some stations the number of days in which the minimum air temperature was below 0°C ( 32ºF ) was more than 15 days, as example Mirada do Douro with 19 days, Sabugal with 18 days and Mirandela, Macedo de Cavaleiros and Carrazeda de Ansiães with 16 days.

The values of precipitation were under the average figures for 1971-2000 reference, described as dry as the standard for December, which contributes to the persistence of the status of dry situation across the country, with 68% of the territory in dry lower level, 31% in moderate drought and 1% in severe drought,  ( Instituto de Meteorologia – ).

On January, 2009, besides moderate snowfall were it was typically expected, but again in some unexpected region as well.

A severe icy week has carried another big surprise for people, with snow accumulation in an important part of Portugal’s Northern and Central regions as well as for the high altitudes.

The country was barely prepared to deal with such a frozen shock. In some areas a few small villages were in fact isolated by snow, disrupting public infrastructures and services for a few days, until it was melted or sublimated.

The official version concerning the above mentioned extend of snow besides the classic regions was that “ the [ atypical ] snowfall occurred in the central and southern regions of mainland Portugal was caused by a low-pressure centre passing along territory, from north to south. The low had formed in a very cold air mass, and an instability line was associated with it.

The air mass was gradually transported in the circulation of an anticyclone located over the British Islands, from Central Europe to the Biscay Gulf and later southwards to the Iberian Peninsula.

During the snowfall, the minimum air temperature reached values as low as 0.5ºC ( 32.9ºF ) at Figueira da Foz ( 10:10 ), 0.4ºC ( 32.7ºF ) at Rio Maior ( 12:50 ), 0.1ºC ( 32.1ºF ) at Santarém ( 13:30 ), 0.4ºC ( 32.7ºF ) at Torres Vedras ( 14:50 ), 0.5ºC ( 32.9ºF ) at Lisbon ( 15:00 ) and 0.8ºC ( 33.4ºF ) at Setúbal ( 16:10 ) “, ( Instituto de Meteorologia – ).

Note that all the above mentioned locations are located out of the small number of expected regions of traditional snowfall or snow-prone areas.

Another interesting conclusion was that the cold air mass was downward from North to South at the expected warmer period of the day.

In February 2009, Serra da Estrela, that is the highest mountain system in our territory and includes mainland Portugal's highest point, had to cope with an 8 meters depth layer of snow, something that was not experienced for many decades.

But February 2009, in terms of precipitation, was classified as normal to dry.

The average amount of precipitation was again below the average once more.

By that reason, the average maximum temperature was slightly higher than the standard value for the 1971-2000 reference periods, with an abnormality of +0.4°C ( 0.7ºF ).

Nevertheless, the values of average temperature and average minimum air were below the reference, with values of -1.3ºC ( -2.3ºF ) and -0.4°C ( -0.7ºF ) respectively, ( Instituto de Meteorologia – ).

However, despite the extremely cold isolated events during last winter, in particular between November 2008 and January 2009, there is a general tendency for a universal average temperature increase.

So far, since the temperature records have began, 1997 it was the warmest year of all.

On the top 10 warm years, 7 took place after 1990 ( 1990, 1995, 1996, 1997, 1998, 2003 and 2006 ).

The summer of 2006 it was the 5th warmest since 1931, just fallowing after 1949, 2003, 2004 and 2005.

I am not conjecturing about the global warming theory, but only pointing that we can in fact be in presence of changing patterns of rainfall, snowfall, and drought.

There are at least evident changes on the climate cycle and on the seasonal distribution of these events with prevalence of a few surprisingly abnormal conditions.

Another evident tendency is the occurring rate of changes in climate, which is now greater than that experienced in the past.

This changing evolution is now expected to accelerate further in the coming decades.

The final results from the fish pond assessment


After the coldest November 2008 ever since on my personal records, a number of cooling days in a December 2008 with particularly low maximum daily temperatures but, above all, an exceptionally frosty period in the beginning of January 2009, some of the less cold tolerant species outdoors were this winter under a severe temperature stress.
The dilemma about last winter’s cold stress wasn’t so much the temperature lower limits achieved, but for the reason that it was one of the longest episodes we can estimate ( at least since the first time when the water temperatures have been registered ).
The so called cold water fish can stay in a winter condition for up to 4 months. During this period of time, when the water is freezing and the surface it is ice covered, they will be mostly dormant, not eating and showing little notice of activity.
Fish from temperate regions can be more or less tolerant but most cannot cope with low temperatures or temperature droppings for long, although they can survive to very intense cold for a few ours or even days.
Small fish ponds of around 50000 liters’ of water capacity or less are very susceptible and vulnerable to air temperature fluctuation. This is particularly true if there is no wind protection and the reservoir is less than 90 cm deep. Deeper ponds and bigger lakes or lager dams are no doubt more thermally independent from air temperature transitions and fish can seek for refuge in the deeper areas during extreme hot and cold episodes.
We are not talking here about a larger local freshwater natural environment but about a relatively small quantity of water, ion a garden fish pond, which can become all of a sudden excessively cold or hot, in face of weather variations, as contrast with the local rivers or bigger reservoirs.
Besides a few revelations, following this last winter, it was a general believe that we can count with two brand new species, fairly well adapted to our local climate.
Allow me also to affirm myself in harmony with Paulo Alves, according to who, “ any fish who manage to live to tell the tale after 2008/2009 winter in outdoors facilities, is no doubt skilled to stay alive during any winter at all in this country “.
The local air temperatures recorded between November 2008 and February 2009 can provide you an idea about what has been assumed before:

This way, it was imperative to complete, as soon as possible, an exhaustive assessment on the fish resident’s dynamic of the garden fishpond, taking in consideration the extreme low temperatures of January 2009, in particular during a certain period of time.
The survey operation took place Monday, the February 23rd 2009.
The procedure was drain out all the water and capture as many fish as possible, filling it up afterwards and replacing fish and plants back again.
Air temperature recorded between 0:00 and 24:00 that day was 7ºC ( 44.6ºF ) and 19ºC ( 66.2ºF ).
Water temperature recorded was 14ºC ( 57.2ºF ) at 6:00 and 15ºC ( 59ºF ) at 18:00.
On the photos published at
Garden fish pond survey on February 23rd, 2009 you can see some of species listed next.

Complete list of captured fish :


Carassius auratus ( aquarium strain - Shubunkin )

Cyprinus carpio x Cyprinus rubrofiscus  ( Koy )

Cyprinodon alvarezi ( El Potosi )

Heterandria formosa ( aquarium strain )

Oryzias latipes ( aquarium strain )

Skiffia multipunctata ( Lago de Camecuaro )

Xenotoca eiseni ( aquarium strain )


The fallowing species did not succeed and have fail to been spotted :


Ameca splendens  ( aquarium strain )

Aphanius mento ( Elbistan )

Fundulus cingulatus ( aquarium strain )

Figure 2 - Xenotoca eiseni, one of the most interesting surprises.

The complete absence of Aphanius mento as well as Fundulus cingulatus was a colossal surprise.

These fish are surprisingly cold tolerant species.
The Fundulus cingulatus founder colony introduced in October 2008, was in fact the same lineage of those raised by Alberto Gil. Such fish are completely acclimated to our winter in a Northern and colder region of this country. They are cultivated for some years in smaller outdoors fishponds all year round.
The somewhat small size of the individuals released on the fishpond, could have turn them in a fairly easy meal for predators ?
Well… who knows, but if that was the case all Heterandria formosa had long vanish too.
Even captured in a rather small number ( only 23 captured ), the presence of the “ Least Killifish “ was no doubt the most unexpected good news. The ancestors of these little fellows were left there for so long, that on my previous message about this subject on the mailing list, in January 26th 2009, the species was not even listed.
Another interesting surprise was Xenotoca eiseni. The survivors were all young adults and fry. The older fish ( and larger ones ) have been all vanish.
Xenotoca eiseni was regarded ( in theory ) as less resistant to low temperatures than Ameca splendens, so it was a dramatic shock to loose several hundred fish of all ages belonging to this last species this season, as they have overcome very well in other tough years, like in 2007/2008 winter.
Our esteemed colleague Martin Ravn Tversted, have written on his article “ Low Temperatures and Cyprinodonts “, that both species can withstand for a good number of days at 10ºC ( 50ºF ) or
incipient lower lethal temperatures, but the good news is that these Xenotoca eiseni were able to cope with 5 days below 8ºC ( 46.4ºF ) and overcome the lowest limit of ever according to my records – 5.4ºC ( 41.72ºF ) – as you can see further below on this text.
With reference to Martin’s own experience, another good surprise was Skiffia multipunctata, staying alive rather close to the mentioned
incipient lower lethal temperatures of 7ºC ( 44,6ºF ).
This was also a nice opportunity to get rid of a few Shubunkin Goldfish ( Carassius auratus ) introduced with eggs on aquatic plants and escapees last time I had the opportunity to perform a maintenance procedure on the fishpond.
Carassius auratus was eradicated this time in order to reduce egg predation on the other egg layers as well as to decrease resources competition with other species.
It was also noteworthy the admirable amount of Red Cherry shrimps captured ( Neocaridina denticulata sinensis ), including rape females with lots of yellowish eggs, besides a remarkable number of very small fry.
Among a considerable quantity of unidentified invertebrate species, a Green Frog or Common Frog ( Rana perezi ) tadpole, almost certainly born last reproduction season, has captured, but no other ones or even frog postures was still present this year.
Another amphibian species found was the Iberian Painted Frog ( Discoglossus galganoi ), but merely two animals were spotted.
For the first time this winter an aquatic plant was vanish.
The so called Java moss ( Vesicularia dubyana ? Taxiphyllum barbieri ? ) here referenced this way, because it is possibly another species like the one from Taiwan ( Taxiphyllum alternans ), because the real Vesicularia dubyana would never support our winter season at all.
There was no more missing plant species so the complete list of flora is this one :

Elodea canadensis
Egeria densa
Lagarosiphon major
Myriophyllum spicatum
Potamogeton nudosus
Potamogeton pectinatus

I’ll simply replicate now a few passages of my late message on the subject of this winter low temperatures, sent to the list last January 26th :

Although daily water temperature records at the fishpond have come in to an end 3 years ago, during extraordinarily extreme weather conditions ( cold or warm ) I continue to check the thermometer in order to maintain an inventory for additional reference.

On the extraordinary frozen days during this last January the records of temperature at the fishpond surface ( 15 cm depth ) are those listed next :

05-01-2009 > 12.3ºC ( 54.1ºF )
06-01-2009 > 10.1ºC ( 50.1ºF )
07-01-2009 > 9.6ºC ( 49.2ºF )
08-01-2009 > 9.2ºC ( 48.5ºF )
09-01-2009 > 7.2ºC ( 44.9ºF )
10-01-2009 > 7.1ºC ( 44.7ºF )
11-01-2009 > 6.4ºC ( 43.5ºF )
12-01-2009 > 5.2ºC ( 41.3ºF )
13-01-2009 > 6.7ºC ( 44.0ºF )
14-01-2009 > 8.3ºC ( 46.9ºF )
15-01-2009 > 10.2ºC ( 50.3ºF )

The coldest day was 9-01-2009, with air temperatures ranging from -1.6ºC ( 29.1ºF ) to 5.2ºC ( 41.3ºF ).
If you take a look at my preceding records in
“ Case Study “ : Garden pond water temperatures, please verify that such intense cold periods are not common at all.
There are two other intense wintry periods moderately comparable to this one between 1985 and 2006.
If you explore January 1992 and January 2005 data, than you will found the last cold uttermost periods and the previous lowest temperature record of 5.5ºC ( 41.9ºF ).
January 2009 unique distinguishing is the fact that, besides a new minimum extreme, the lowest value did not took place on the coldest day but 3 days later.
It seams obvious that there was an apparent delay effect as well as a clear tendency to low down caused by a long period of air freezing.
For future reference we kept also the coldest November of ever ( 2008 ) and a “ gelid “ January ( 2009 ) with a new low temperature limit, since first records were registered back in 1985.



J.L. Kelley, A.E. Magurran and C. Macý´as-Garcia, 2005. The influence of rearing experience on the behavior of an endangered Mexican fish, Skiffia multipunctata, Biological Conservation 122 (2005), pp. 223–230.


Paredes, D., Trigo, Ricardo M., Garcia-Herrera, Ricardo and Trigo, Isabel Franco, 2006. Understanding Precipitation Changes in Iberia in Early Spring: Weather Typing and Storm-Tracking Approaches. Journal of Hydrometeorology, Volume 7, Meteorological Society, February 2006, pp. 101 – 113.


Pereira, J., and Coauthors, 2002. Forests and biodiversity. Climate Change in Portugal: Scenarios, Impacts and Adaptation Measures — SIAM, F. D. Santos, K. Forbes, and R. Moita, Eds., Gradiva, 363–414.


Vlachos, E., and F. N. Correia, 1999. Shared Water Systems and Transboundary Issues: With Special Emphasis on the Iberian Peninsula. Luso-American Foundation, 454 pp.


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