Water Changes And Fish Health- Scientific Studies

[TwoTankAmin]

Since I have been busy it has taken me a while to get information together. Now that I have I find the thread has been locked, so I will post it here. (Italics indicate my comment and are not quotes.)

Whole Effluent Toxicity Testing: Ion Imbalance. From SETAC
Ion Imbalance http/www.setac.org/htdocs/files/TIP-Ion.pdf
This explains ion imbalances and how they can effect fish and what things are potentially most harmful in this regard.

Effect of copper on blood coagulation of Oreochromis mossambicus (Cichlidae)
http/www.sciencedirect.com/science?_ob=A...309503ce0799f45

The effect of copper on the blood coagulation in freshwater fish, Oreochromis mossambicus was investigated. These fish were exposed to sublethal copper concentrations over short-term (96 hr) and long-term (4 wk) periods, at 29 ± 1 °C (summer) and 19 ± 1 °C (winter), in experimental flow-through systems. Copper concentrations applied during short-term exposures were 0.16 mg/ l and 0.40 mg/l, respectively, while 0.40 mg/l copper was applied during the long-term exposures. After a photocymographic observation of blood, during all the phases of coagulation was made, it was evident that there were delays in the blood coagulation times, as well as decreases in the shear modulus (elasticity) of the clots formed, after the exposure of the fish to copper concentrations at both temperatures. Copper was found to induce haemophilia at 29 ± 1 °C and 19 ± 1 °C, while at the latter it also induced thrombocytopenia. Thus exposure to copper lead to coagulation defects, which caused haemorrhage in the body tissue, which can eventually cause the death of those fish.

Active biomonitoring in freshwater environments: early warning signals from biomarkers in assessing biological effects of diffuse sources of pollutants
http/www.sciencedirect.com/science?_ob=A...5a960fdd43740ed

Effects of field exposure were determined using cellular biomarkers e.g. DNA damage, HSP 70, metallothionein, acetylcholine esterase, lactate dehydrogenase and ethoxyresorufin-o-deethylase activity. The results clearly indicate that although the traditional mortality-based whole effluent toxicity testing did not indicate any toxicity, the in situ exposed organisms were stressed.

Understanding what can damage fish is more sophisticated than the WET method of testing- ie damage can be present but not detected by this method.

Environmental context determines nitrate toxicity in Southern toad (Bufo terrestris) tadpoles
http/www.sciencedirect.com/science?_ob=A...537bfb134b0a80f
Based on information from other studies, we conclude that, in ROe water, tadpoles exhibited an expected stress response to nitrate (e.g. metamorphosed earlier as nitrate concentration increased).
Nitrate does seem to have a measurable detrimental effect.

Nitrate toxicity to aquatic animals: a review with new data for freshwater invertebrates
http/www.sciencedirect.com/science?_ob=A...f003c89ddaca62d

Published data on nitrate () toxicity to freshwater and marine animals are reviewed. New data on nitrate toxicity to the freshwater invertebrates Eulimnogammarus toletanus, Echinogammarus echinosetosus and Hydropsyche exocellata are also presented. The main toxic action of nitrate is due to the conversion of oxygen-carrying pigments to forms that are incapable of carrying oxygen. Nitrate toxicity to aquatic animals increases with increasing nitrate concentrations and exposure times. In contrast, nitrate toxicity may decrease with increasing body size, water salinity, and environmental adaptation. Freshwater animals appear to be more sensitive to nitrate than marine animals. A nitrate concentration of 10 mg NO3-N/l (USA federal maximum level for drinking water) can adversely affect, at least during long-term exposures, freshwater invertebrates (E. toletanus, E. echinosetosus, Cheumatopsyche pettiti, Hydropsyche occidentalis), fishes (Oncorhynchus mykiss, Oncorhynchus tshawytscha, Salmo clarki), and amphibians (Pseudacris triseriata, Rana pipiens, Rana temporaria, Bufo bufo). Safe levels below this nitrate concentration are recommended to protect sensitive freshwater animals from nitrate pollution. Furthermore, a maximum level of 2 mg NO3-N/l would be appropriate for protecting the most sensitive freshwater species.

Effect Of Water Exchange On Water QualityAnd The Production Of Ornamental Carp (Cyprinus Carpio Var Koi L.) Cultured In Concrete Tanksmanured With Poulty Excreta
[url[http/www.infish.com.pl/Arch-Fish-Pol/work-pdf/Vol13Fasc1/Vol13fasc1%20-%20w07.pdf[/url]
A study showing more frequent water changes resulted in "better" fish.

Basically the more I hunted for scientific articles the more certain I became of a few things. Most fish keepers are unable to test for some of the most potentially dangerous substances that can build up in their tanks due to the lack of adequate affordable tests. Closed systems such as fish farms present special problems the solutions to which have varied success levels and which are totally impractical for hobbyists even to consider trying to duplicate. Further metals and chemicals which have been demonstrated as being toxic to aquatic life are like present in most of water systems having been introduced to a myriad of variables which can include being introduced in ways we may not realize are occuring. And most importantly- frequent regrular water changes are the best methods for preventing many problems.

If you would like to see some of the many studies out there, use the Google Scholar search and plud in "TDS Toxicity + Fish" or "Nitrate Toxicity + Fish".

 

[andywg]

This would be better added to the thread which was linked in the thread you mention being closed (hence why that thread was closed, there is little point having two threads on the same topic open). Hopefully a mod will move it across and the discussion can resume there.

Edit

For ease, this is the original (still open) thread:

http/www.fishforums.net/content/Scientif...mal-Parameters/

 

[Spider Pig]

As I understand your posts from the previous thread, your contention was that it is negligent to perform water changes less than once every 4-6 weeks, and the studies outlined in your post support this hypothesis

Whole Effluent Toxicity Testing: Ion Imbalance. From SETAC- This paper identifies imbalance of dissolved ions as a cause of morbidity in aquatic life. However there is no indication from this to support the contention that not doing a water change every 4-6 weeks will lead to this ion imbalance. TDS concentration can be reduced in other ways such as plant growth

Effect of copper on blood coagulation of Oreochromis mossambicus (Cichlidae)- this paper shows that copper can be a cause of morbidity in aquatic life. However there is no indication from this to support the contention that not doing a water change every 4-6 weeks will lead to this level of copper concentration. Heavy metals can be removed from the water by carbon filtration or plant growth such as silvania natans

Active biomonitoring in freshwater environments: early warning signals from biomarkers in assessing biological effects of diffuse sources of pollutants. This study indicates that current measures of morbidity may be unreliable. However that doesn't support the contention of negligence in performing water changes less that every 4-6 weeks. It may be an argument to err on the side of caution however.

Nitrate is a well recognised cause of morbidity. I would be surprised if the majority of aquarists keep their nitrate level below 2mg/ ml. Many tapwater sources have nitrate above this level and so this is likely to aggravate a problem. Nitrate can be reduced by methods other than water change, such as plant growth.

Effect Of Water Exchange On Water QualityAnd The Production Of Ornamental Carp (Cyprinus Carpio Var Koi L.) Cultured In Concrete Tanksmanured With Poulty Excreta. This study shows that if you keep throwing chicken poo in your aquarium your fish will do better if you do regular water changes as unsuprisingly nitrate, nitrite ammonia and others is higher in tanks where regular water changes aren't done. Whilst a valid warning to people who do use chicken poo in their aquarium, I think this has limited applicability to the conventional home aquarium and still doesn't support your contention that it is necessary to do water changes every 4-6 weeks.

From the studies I found most of the problems faced in closed system fish farms centred around nitrogen waste and phosphate. I disagree with your contention that this cannot be dealt with in the home aquarium. The solution is again our green friends, plants. This is best demonstrated by low light low tech aquariums and the work of Diana Walstad, where it has actually been stated that regular water changes can be deleterious to the aquarium. The links are given at the end of the thread tagged by andywg above.