Guppies originate from the rivers and brackish estuaries in Trinidad and the northern and central parts of the Americas. Scientists have found them in warm springs and their effluents, weedy ditches and canals. They are found in highly turbid water in ponds, canals and ditches at low elevations to pristine mountain streams at high elevations. The wild guppy has adapted to a variety of habitats with a variety of water conditions.
Modern tank-raised guppies are several hundred generations removed from their wild ancestors, so it’s dangerous to generalize about the water parameters they are “naturally” adapted to. Scientific studies have shown that many fish have a genetic potential to adapt to new and different water conditions. When the Suez Canal was built, it formed a conduit between two very different water bodies and the fish that migrated through the canal slowly adapted over many generations to the very different waters of the two bodies the canal connects. While fishing in a river that empties into the Gulf of Mexico, saltwater red snapper can be caught in the middle of the river and freshwater bluegill and bass along the edges. This was inland over 15 miles and they could be caught anytime of the year, these fish must have adapted.
The guppy’s adaptability to water with relatively high salinity content has been studied (Strain differences in seawater adaptability in newborn guppy Poecilia reticulata, Shikano,-Takahito; Fujio,-Yoshihisa, Fish-Sci 1998 vol. 64, no. 6, pp. 987-988). Scientists found the fry born from mothers adapted to high salinity water (35 ppt), survived at a greater rate than fry born from mothers not adapted to high salinity water. And here is the most important point: the authors found that the survival rates of the fry varied significantly among different strains. This strongly suggests that there is a huge variance in the genetic potential for adapting to change among guppy strains.
The scientific study is supported by anecdotal evidence from guppy breeders who maintain that guppies born and raised in local water conditions have a much better survival rate than guppies from distant areas with dissimilar water parameters. It is also reported that some strains are hardier than others. For example, swordtails have the reputation for being hardier than delta tails.
In the wild, nature selects tough guppies with the genes for surviving adverse water conditions and disease. Human select show guppies for visual appearance. It’s not surprising that guppies have lost their reputation for being indestructible, although some people blame the increased tendency of guppies to become diseased on the introduction of exotic diseases from Asia over the past few decades and the development of anti-biotic resistant bacteria strains. This is an oversimplification. By virtue of the fact that the majority of people select guppies for human aesthetic reasons rather than health, everybody is contributing to the problem.
An immediate sign of the guppy’s adverse reaction to water changes is fraying of fins. Contemporary guppy’s long fins are often too thin and therefore fragile. For example, moving a fish from one tank to another may result in split tails if the temperature varies more than two degrees between the aquariums.
These guppies at a show have been placed in water that is quite different from their home tank. They are showing signs of stress, hanging near the surface of the bowl.
Other indications of the guppy’s adverse reaction to sudden water changes are that they hover near the surface or begin to shimmy. Their fins may clamp. The guppies may become shy, although they may also just be frightened in their new environment. If shyness persists more than a day, and it is accompanied by other signs, than it is probably poor water quality. See the Guppy Library of Diseases and Treatments for the article on Poor Water Quality.
You should always prepare in advance for the introduction of guppies from another area to your tanks. Water conditions in North America vary widely from one state or province to another. The water on the eastern seaboard is and the Pacific Northwest is very soft, while in the Midwest and the West Coast, the water is very hard. Even wells on different parts of a property can have quite different water parameters. In areas of hard water, homes are often fitted with water softeners.
When introducing guppies from another person’s tanks, the advice most commonly provided is to slowly adapt guppies to your water conditions (over several weeks, not several hours), and not expect new fish to do well until the next generation is raised in your tanks.
If you have water conditions at the extremes of the guppy’s range, it’s a good idea, especially for novices, to moderate conditions. The danger all breeders face is that the guppies weakened through living at the extreme ends of their range are less capable of absorbing the impact of other adverse factors, such as a sudden change in temperature, or a gradual rise in the level of ammonia in the tank. Creating the optimal conditions for guppies can allow novices to experiment with other factors affecting guppy health, such as feeding, without immediately endangering their fish.
Stable Water Conditions
Guppies do best in water that is slightly alkaline and moderately hard. Stabilizing the water conditions so that they stay near these parameters is the overarching goal of a good water management system.
The majority of guppy breeders in North America live in areas with naturally hard water, so the most common advice you hear is to adjust guppies to local water conditions. However, breeders who live in areas where the water is naturally soft will tell you that guppies do not fare well in soft water. Breeders living in areas where water is soft will probably have to add chemicals to harden their water. Given that they will often be importing guppies from hard water areas, adding chemicals to harden the water is probably a good long-term strategy.
As a general rule, guppies will do much better in water that is a little too hard or a little too alkaline than water that is too soft or too acidic. A corollary rule is that rapid changing the water to conditions a guppy is comfortable in is better than rapid changes away from its comfort zone. However, rapid change is not good for guppies, period.
People who boast that they can grow guppies in water outside their range of preferred conditions are playing with a time bomb. All the factors affecting a guppy’s health, including diet, light, natural or acquired immunity, the state of the nitrogen cycle and the tank chemistry are intertwined. Guppies living at the extremes of their tolerances will often suddenly and quickly fall apart. A sudden drop in temperature, a blood worm infested with a pathogen, a new fish… the spark that lights the fuse of the time bomb will blow up your tank of show fish quickly indeed.
So here is the goal of a good water management system once again: Stabilize your tank to water that is slightly alkaline and moderately hard.
Larry Reinhardt Comments
If you have the dedication and good sense to follow what’s been written above then it’s certainly prudent to do so. All that is written above I completely agree with, however what I think happens in the real world is not as it should be. There aren’t many who will enquire about the water conditions of the guppies they are receiving. For years as a hobbyist I sold fish to LFS and when I started my first farm I had a lot of local customers and then I started shipping to pet shops around the country. Only on two occasions did anyone ask me about my water conditions, I remember because it was so unusual. Frankly that’s not on people’s list of things to do. In my personal fish room and on my two farms I raised my fish in the water of the local area, which at least made for happier local customers. I purchased 3 strains of IFGA guppies to introduce into the strains on my 100 acre farm, but that failed; they died without dropping any fry. The guppies that were being raised there had been there for years, its water was acid and soft.
Within the guppy community are dedicated people who will enquire about the water, realizing the nature of the fish we keep. Even then the majority will not do much beyond an initial adjustment if the water parameters are too diverse from ideal. Hobbyist with circulating systems or who draw their water from a large sump tank can make these chemical adjustments with a reasonable amount of labor and expense, but they are a minority. Most of us who have gone beyond beginner to novice to serious hobbyist have individual tanks. Those whose water is reasonably close to ideal are very fortunate indeed, but the unfortunate and there are many have a decision to make.
Pamper your fish and raise a couple genrations from young breeders, or sadly watch then waste away.
Philip Shaddock Comments
As Larry says, most hobbyists don’t bother to proper acclimatize, quarantine and chemically delouse their guppies when they acquire new stock. However, I think when you have been in the hobby for a long time and have developed strains that cannot be replaced, you become more cautious. I have found adjusting the pH of the receiving tank to the same pH as the water of the incoming guppies, isolating the new guppies to some extent for at least a month (and gradually acclimatizing them to local water conditions during that period) and medicating them to remove the most common parasites saves a huge amount of grief in the long run. I think you play a game of Russian Roulette in just dumping new guppies into your existing system. Most of the time nothing adverse will happen and you may even stimulate your existing guppies immune system. But very occasionally you will introduce guppies that act as carriers of a disease they are immune to but which the guppies in your tank or fish room have no immunity. Disaster strikes. It’s a lottery you do not want to play because it is a lottery where you win most of the time and then lose everything. Not worth the odds in my opinion.