Stomach Pump Questions


Active Member
Sounds a lot less lethal, throat pump V stomach pump. There are times when sampling a trout's throat does give the fly fisherman an advantage. Ethical, harmful, no harm, legal, proper? Let your conscience be your guide.

I have to wonder if studies on resulting mortality have ever been done.
Also proper? and improper use guidelines.
I guess there's always the good old fashioned 'gut one and keep it' method where allowed.

Seriously, I think discussing this is a good topic that goes along with c&r and proper handling.


Triploid, Humpy & Seaplane Hater....Know Grizzler
I don’t have a problem with people using them if used properly.
They are designed to pump the throat, not empty their stomachs.
Many times the insects, bugs etc you pump are still alive.
I’ve had a few days where I had only had caught one fish up to a point after trying multiple patterns.
Sure, I caught a fish but does that mean the fish are necessarily keying on the pattern I was using?
Pumping the one fish I caught told me they were not and a pattern change to match what I had pumped resulted in a good day of fishing.


Active Member
Occasionally I take a throat sample on a trout. I learned how by watching Brian Chan perform samples on his instructional dvds. I never have pumped any trout's stomach, throat or vent and following Brian's recommendation never on a trout under 12".


Active Member
I do use one on occasion but it's generally after exhausting my usual standby patterns.
That said I won't pump a fish that's too small or a larger one that might be exhausted from a longer fight. Also, I won't photograph a big fish for the same reason.
Usually I fish with several others and we just compare and share to crack the code.

BTW, the store bought pumps have a squared off end on the tubing so I have tapered all of mine with super fine sandpaper to hopefully be easier on the few fish I do pump.

Dave Boyle

Active Member
Something I’ve observed over time is not to sample a fish where it takes sometime time to get it to the net. They have nothing when ‘pumped’

In other words like marlin and sailfish as an example I know of, fish puke while fighting for their lives so I’d argue sampling after capture doesn’t cause a death sentence via lack of nutrients. Fighting fish for too long might though.

I don’t do this much but if fishing is tough then I do. The issue is learning to do it correctly, if you think about it, it is a brief flush and does not involve the stomach in any way. The device I bought had no rough edges at the input end but worth checking if you want to do this.



Joel K

New Member
I think it mostly depends on what the opposite hand is doing to the fish. If your holding it by the body, the fish may be in trouble. Just my opinion.

Good fishing!


WFF Supporter
Stomach pumps really bother me for various reasons.

First does the person doing it really know how to do it correctly and not damage a fish. and by the way I have had a tube shoved down my throat and found it not very pleasant.

If a person has already caught a fish it should be more or less obvious of what the fish are eating so why subject said fish to possible mortal damage by shoving a tube down its throat. As far as I am concerned just kill the fish and gut it. If you are a skilled biologist or ichthyologist that really knows what you are doing maybe that is different but only by a little.


Sounds a lot less lethal, throat pump V stomach pump. There are times when sampling a trout's throat does give the fly fisherman an advantage. Ethical, harmful, no harm, legal, proper? Let your conscience be your guide.

I have to wonder if studies on resulting mortality have ever been done.

Also proper? and improper use guidelines.

I guess there's always the good old fashioned 'gut one and keep it' method where allowed.

Seriously, I think discussing this is a good topic that goes along with c&r and proper handling.

The above replies are common reactions to the use of stomach pumps.

Before catch and release became the way most fly fishers fished, fly fishers kept, cleaned and ate their catch. They had a very important advantage over a C&R fly fisher. By cleaning the fish, they gained knowledge about what the fish was eating when it was caught. So they could correlate what they observed on the stream and what fly they used to catch the fish, with what the fish was actually eating.

When a fly fisher releases a fish, he has no knowledge about what the fish actually ate before he took the fly. There is a way to gain that knowledge without much additional harm the fish any more than we do by taking additional time to photograph the fish.

I have studied the scientific fisheries literature on "stomach pumps" as well as participated on several discussions on fly fishing BBs.

There are two main objections that fly fishers often raise about the use of stomach pumps. The first is that the anger is robbing the fish of energy by taking food from the fish. The second is that stomach pumps kill fish.

First to the argument that we are taking food out of the fish and robbing it of energy. The fact is that the fish uses up more of its store of energy during the fight to escape us than we take by sampling its throat. The argument that we are "robbing" the fish of food and energy is a hollow argument when made by a fly fisher whose goal is to hook a fish and fight it until it can resist no longer.

As to the argument that stomach pumps kill fish, stomach pumps have been scientifically studied and they have very low mortality. Certainly catching the fish places the fish at greater risk than a stomach pump and much greater risk than doing a shocking survey on fish. I strongly believe they are less stressful that the grip and grin photos we all take from time to time.

"Strange and Kennedy (1981) assessed the survival of salmonids subjected to stomach flushing and found no difference between stomach-flushed fish and control fish that were held for 3 to 5 nights."

Stomach pump article: Methods Examining Fish Stomach Contents"

In the article above, the goal was to remove stomach contents. The goal of a fly fisher is to remove the throat contents which are the last few items eaten. Throat sampling is less invasive than stomach sampling.

The New Fly Fisher - Tip #28: Throat Pumps - YouTube

Tom Rosenbauer talked about stomach pumps on a podcast, Tom's Ten Tips for Identifying and Matching the Hatch

Tom starts discussing stomach pumps at about 20:58 into the podcast. He says, ""I'm not so sure how safe that is for trout. …… I don't think there have been any studies done on mortality of fish that have had their stomach pumped. Probably most of them survive but you never know….."

I have corresponded with Tom Rosenbauer after he made those comments and I sent the research on stomach pumps to him. In his podcasts since then he endorses stomach pumps and in his podcast (8/15/14 on Steelhead), in the fly box section, he talks about his findings when stomach pumping trout. So Rosenbauer is on board with stomach pumps.

Carl Richards and Doug Swisher of Selective Trout fame used stomach pumps to gain the knowledge to write that book. Carl Richards wrote the chapter titled What Trout Eat in the The Complete Guide to Fishing with a Fly Rod published by Fly Fisherman Magazine, ISBN: 0-87165-013-4.

The stomach pump is given over 3/4ths of a page coverage in picture and text on page 46. I quote from the text, "If fish are feeding underwater, two methods can be used to discover what they are feeding on. The best way is to catch a fish (usually one dummy can be taken using an attractor, fished wet, such as a Coachman) and pump his stomach with a simple stomach pump." From the caption for the pictures, "Above, a stomach designed for trout is an effective way of discovering what the fish are feeding on without harming it."

More recently, Brian Chan has also recommended "stomach" pumps as a method of safe sampling. As a Senior Fisheries Biologist, he is probably aware of the above scientific article from reviews in Fisheries Science.

Ruby Mountain Fly Fishers: Throat Pumping Trout

Fly Angler's OnLine "Deanna Birkholm - Ladyfisher's Article - 9798"

This is the method that I use:

Fill the pump completely water and then push out 1/2 of the water by compressing the bulb. Insert the tube gently into the throat and release the bulb so the remaining 1/2 of the bulb re-expands sucking up the food into the plastic stem. If nothing comes out, then without pulling out the tube, compress the bulb gently push in some of the water and then suck it back but don't suck material back into the bulb. Now release the trout.

The material in the tube should come out in the order that the fish ate it with the last item out being the one the fish ate last. You should not have the items into the bulb or else they will get mixed up and you won't know for sure what was eaten last. If you did suck material into the bulb, examine the food and the freshest item was probably eaten last.

I rarely pump now since I usually know what the fish are eating. However, for the beginning fly fisher it is a wonderful educational tool. A portable sampling net and the stomach pump forms the two best methods of learning what the fish are eating.

The best way IMHO to sample a fish with stomach pump is first to net the fish, no matter what it's size. Then before even taking off the hook, keep it in the net and in the water. Turn the fish upside down. This is almost always disorients the fish and keeps it from struggling. Quickly sample the fish, then drop the pump into the net, remove the hook and release the fish.

You can then examine the sample after releasing the fish. This method is the least traumatic and I have found it to be the fastest way to release the fish. It rarely takes significantly longer than most people take to just remove the hook and release the fish. It is better than lifting the fish out of the water.

The third argument against stomach pumps is that it is unsporting to use a stomach pump.

Like many techniques in fly fishing, I believe using a stomach pump is what could be termed a fairness issue. Some fly fishers feel that nymphing is somehow unfair, and some nymphers think nymphing with strike indicators is less fair than fishing without. The Dry Fly vs Nymphing ethical argument originated with Halford and Skues and in some circles that argument continues to this day.

Halford and Skues: "This Chalkstream Ain't Big Enough for the Both of Us" | MidCurrent

So if you don't want to use a stomach pump, don't. But research has shown that stomach pumps are not a resource issue.

The experienced fly fisher has little need to throat pump a fish. But for a beginner, I think it is a valuable learning tool that does not harm the resource.

A throat pump is especially valuable when used in the context of fishing emergers. Emergers can be a difficult for beginners to sort out and a throat pump is one of the best tools in figuring out what is actually happening. Hence my suggestion that a throat pump is a valuable tool to study emergence.

Truth be told, the greatest threat to a trout is the most effective fly fisher because they catch the most fish. Studies have shown that hooking mortality even with barbless hooks is 3.5 - 4%. We inadvertently kill 1 of every 25 fish we catch. Catch and release 1000 fish in a season and you have killed 40 fish. I have had 50 fish days on the San Juan and two trout probably died.

One of the purposes of this BB is to to educate fly fishers on how to catch more and more fish, but we do not consider this an ethical issue. Fly fishers, and I include myself, tend to forget that even C&R fishing with a fly is a blood sport.

The reality is that as we become more adept at catching fish, more fish will die regardless of how careful we are.

I carry a stomach pump out of habit but I have not used it in several years. But I know I have killed quite a few trout over those years simply by the act of catching and releasing them. No matter how careful we are fish will die.

As I have written before on the barbed vs barbless hook issue, what really matters is that the additional mortality from C & R fishing with barbed hooks is so low (4.5% for barbed hooks and 4.2% for barbless hooks) and the compared to the natural mortality rates for wild trout so high (30-65% annually) that the differential mortality of 0.3 % for barbed hooks is meaningless. The same logic holds for the use of stomach pumps.

Stomach pumps are not a resource issue.


Active Member
I rarely pump now since I usually know what the fish are eating. However, for the beginning fly fisher it is a wonderful educational tool. A portable sampling net and the stomach pump forms the two best methods of learning what the fish are eating.

Great post silvercreek. I don't carry a stomach pump while fishing, but I have nothing against them. I pumped hundreds of stomachs as part of my post-doctoral research on salmonid feeding behavior, and we had no problem getting permits and no signs of mortality associated with the pumping. We were working with anesthetized fish, but we were also using a more invasive method to remove almost 100 % of the stomach contents.

If someone is handling fish in a way that's close to killing it anyway, for example after playing it for too long or in very warm water, then the little bit of extra stress and extra time out of he water for pumping might push it over the edge. I'd be surprised if there aren't a few fish killed that way, but I bet the number is extremely low. If people carrying stomach pumps are careful to only use them on fish that haven't been exhausted by a fight in marginal temperatures, and to keep the fish mostly in the water in their net during the process, then I think they can feel pretty good about what they're doing.

I mostly don't carry one for similar reasons to why you don't use yours much: I've studied fish and bugs enough to tell what's generally going on most of the time. That doesn't mean I always know what fly to use -- I found myself shouting in frustration, "What are you eating???" at finicky trout a few times on my most recent trip to Yellowstone. But pumping the stomach of a different trout wouldn't have given me the answer to what the current trout is eating, because frequently they're eating different things than they were a few minutes ago, or different fish in the same pool are focusing on different prey. There are also times when the fish are eating a mixed bag of prey and very hard to predict, but that's when any well-presented attractor fly should do the trick.

Pumping stomachs is a nice way to learn what kind of food has generally been available to the fish recently. However, you can also get that information through knowledge of entomology, observational skills, and experience reading difficult fish. With that skill set, carefully scanning the water and knowing how to interpret riseforms can tell you more about what what the next fish is eating than you can learn from the stomach contents of the previous fish you caught. So I see pumping stomachs as more of a learning tool to help build those skills.


Living at the place of many waters
WFF Supporter
I did not get one, just been working on observational skills like mentioned. I harvested two fish yesterday, and put the contents in a glass cup. There was noting in there that I wasn't seeing in and around the stream. Lots of tiny stuff I don't mess with, and naturals of what I've chosen to offer based on my observations. Very few winged adults and lots of nymphs.

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