Oxygen and temperature fluctuations alter goldfish gills

Image Source: The Goldfish Bowl: Canterbury Writers

Gills are to fish what lungs are to mammals. This is where gas exchange between the animal and the environment takes place. As water flows across the gills, oxygen is taken up into the blood of the fish and carbon dioxide is removed. In both systems, oxygen is transported throughout the body by binding to hemoglobin molecules within red blood cells.

goldfish gills.jpg
Image of goldfish gills from: How to take care of a goldfish: Pet goldfish care guide


Researchers Velislava Tzaneva, Shawn Bailey, and Steve F. Perry from the Department of Biology at the University of Ottawa have been studying how the structure of goldfish gills change with varying environmental conditions. They were specifically interested in the build-up of cells on the lamellae termed the interlamellar cell mass (ILCM). Looking at the diagram above, you can imagine how large ILCMs would limit the surface area available for gas and ion exchange across the gills.

Their findings were recently published in The American Journal of Physiology and show that exposure of fish to phenylhydrazine (PHZ), to reduce red blood cell counts, results in loss of the ILCM. Likewise, exposure of fish to carbon monoxide (CO), to prevent oxygen binding to hemoglobin, reduces the ILCM compared to the gills of untreated fish shown in panel A. Both treatments reduced the oxygen content in the blood of these fish (hypoxia) while the environmental oxygen levels were kept constant. What these findings mean is that even though the fish were able to sense normal environmental oxygen levels, blood levels of oxygen could be impacted by changes in the oxygen carrying capacity of blood. By reducing the ILCM, the fish are attempting to increase their uptake of environmental oxygen. These findings are shown in figure 3 from the paper:

C__Documents and Settings_ksweazea_Local Settings_Application Data_Mozilla_Firefox_Profiles_3uu0pmfk.bmp

Exposing fish to conditions of high oxygen levels (hyperoxia) has the opposite effect and promotes the build-up of the ILCM. This effect appears to be dependent on temperature since fish housed at 7 degrees Celsius develop more ILCM compared to fish housed at 25 degrees, which is roughly room temperature. Since warm water contains less oxygen than cold water, these findings again show that the size of the ILCM depends on the oxygen content of the water. Having a smaller ILCM provides more surface area for gas exchange and the uptake of more oxygen into the blood when environmental levels are low. In contrast, a larger ILCM reduces gas exchange when environmental levels of oxygen are high.


By injecting the buccal cavity of fish with sodium cyanide, which activates oxygen receptors, they were able to determine that the remodeling of the ILCM is driven at least in part by these chemoreceptors.

The findings in this study shed some light on how fish adapt to changing environmental conditions.


Evans DH, Piermarini PM, Choe KP. The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste. Physiol Rev. vol. 85:97-177, 2005.

Tzaneva V, Bailey S, Perry SF. The interactive effects of hypoxemia, hyperoxia, and temperature on the gill morphology of goldfish (Carassius auratus). Am J Physiol Regul Integr Comp Physiol 300: R1344 -R1351, 2011.

More like this

Image of zebrafish By Pogrebnoj-Alexandroff from Wikimedia Commons We tend to think of carbon monoxide (CO) only in terms of being a poisonous gas. The reason for its toxicity is due to its ability to bind really tightly to our hemoglobin molecules, which prevents oxygen from being able to bind…
Hemoglobin is a protein within mammalian red blood cells that transports oxygen for delivery to tissues throughout the body. Antarctic icefish (Channichthyidae), like the crocodile icefish pictured above, are quite unique in being reportedly the only vertebrate that does not have circulating…
With all the vaccination "skeptics" who've crawled out of the woodwork over the last couple of days in response to my two posts about Dawn Winkler, the Libertarian candidate for the Governor of Colorado who happens to be a rabid antivaccination activist, not to mention totally clueless and nasty…
Photo: Blue crab being monitored for metabolism using a respirometer, courtesy of Louis and Karen Burnett. Based on information presented at the Global Change and Global Science: Comparative Physiology in a Changing World conference, August 4-7, 2010 in Westminster, Colorado. Louis Burnett,…