My computer is back online and I was able to copy an excerpt from my upcoming book:
A note on respiration rates
Aquarists are warned throughout this book about rapid breathing in their fish as a symptom of potential problems, yet few know just what “rapid” is. Obviously, fish kept in warmer water or those with gill disease will respire more rapidly. Actively swimming fish respire faster than sedentary ones. Less obvious is that larger fish respire more slowly and, in some cases, high ammonia levels will cause a fish to respire more slowly than normal. While there is some difference between species, (Chinese algae eaters will breathe twice as fast as any other fish their size) most tropical fish of the size kept in smaller aquariums should breathe at a rate of between 70 and 120 gill beats per minute. Relative respiration rate is the most important value – capturing the respiration rate of your fish when they are known to be healthy, gives you a baseline to compare to if you later suspect a problem. Not having this baseline data is an issue for newly acquired fish, so using the information below may serve as a secondary reference.
Fish may exhibit a variety of respiration forms in addition to the actual rate itself:
Mouth open respiration – may be a sign of gill disease or toxic compounds in the water.
Rapid, shallow respiration – may be signs as above, or just a result of high activity level.
Coughing – a result of high levels of particulates in the water, or gill parasites.
Gasping at surface – usually seen in freshwater fish under low oxygen conditions.
Slow, deep respiration – may be normal, or a sign of ammonia toxicity.
Slow, shallow respiration – normal for most fishes.
Pomacanthid angelfish are sometimes known to breathe using only one operculum. They can switch back and forth, and then return to breathing with both opercula, all for no discernable reason. Emperor angelfish, Pomacanthus imperator and moray eels are well known “skip breathers”.
Apparently healthy Emperor angelfish will sometimes breath using just one operculum. They can also “skip breathe”.
Some fish simply do not hold still long enough for the aquarist to accurately count their respiration rate. In these cases, try to measure the rate for 15 seconds. Repeat this multiple times and then average the result and multiply that by four to get an average gill beat per minute value. For rapidly swimming fish, you can try setting a cadence to the few breaths you can see, and then tap your finger keeping count at the same rate if the fish’s gills become obscured. Another option is to video capture your subject and then count the respiration rate from the video – giving the option of pausing and repeating the video for a more accurate count.
A database of over 300 samples of fish respiration rates was developed. Variables such as water temperature, fish size and “normality” were recorded. From this, estimated respiration rates for other fish could be established. Because this data cannot easily be presented in written form, some of the data has been extracted here:
Slowest respiration rate: 6 gill beats per minute for a 9” rockfish at 48 degrees F.
Quickest respiration rate for a healthy fish: 217 BPM for a 3” algae eater at 78 degrees F.
Quickest resp. rate for an unhealthy fish: 200 BPM for a butterflyfish with marine Ich
Quickest resp. rate for a healthy fish: 160 BPM for small butterflyfish at 82 F.
Average resp. rate for entire database: 60 BPM
Average size for all fish in database: 12”
Average water temperature for all database samples: 76 F.
