After reading good things from Meadowlark (btw welcome back!) about Gambusia Minnows i would love to add them to my forage base. However, i have read that Gambusia minnows outcompete fish of the same size (like fathead minnows) and in a lot of cases will eat fathead minnow fry. Is it possible for both species to thrive in the same pond? A variable that will probably play a factor in this is the size of the body of water. In my case it is a 1/2 acre pond.

Whether this info is true or not, I am not willing to risk my fathead minnow population at the moment. However, if someone has more experience with these fish and would like to offer there thoughts on the subject please do. I would love another species of minnow for my trout pond.

Please, if possible how does the Gambusia minnow compare to the fathead in spawning rate and prolificness (sp)? I imagine that the Gambusia has a lot less young as it is a livebearer.

Also how do the two compare as to ease of capture by predator fish?


Thanks, I don't mean to stir anything up with this post, I am sincerely interested in this.

- Jighead

Jighead:

IIRC, you are using FH as forage for trout. I can't remember if your have a separate forage pond or not.

Jighead,

Thanks for the welcome and great to hear from you again. How are those trout doing?

First, my experience with FH and Gambusia is all in warmwater ponds and fishes. My remarks have to be qualified by that.

Is it possible for both species to thrive in the same pond?

In my warmwater ponds with predators such as HSB and/or LMB, the FH simply do not survive....regardless of the presence of Gambusia. In spite of very favorable spawning structure, the FH do not survive past one growing season due to predation....but that isn't all bad. After all, the purpose of the FH is to be eaten by predators and they are good at accomplishing that. The FH are a great starter forage, but extremely expensive on a recurring basis.

I have Gambusia in ponds large and small...doesn't seem to matter. They have flourished in one old LMB pond for an estimated 75 years without intervention, i.e. pond management.

As to spawning rates, Gambusia spawn every 28 days. I don't know the numbers for comparison to FHs, but a fish that survives to spawn is certainly more prolific than a dead fish that has been eaten.

Also how do the two compare as to ease of capture by predator fish?

Clearly, the FH is far easier to catch. I've seen them swimming, very briefly, near the top of the water column in wide open water. The life expectancy with that kind of behavior is virtually zilch. The Gambusia, on the other hand, hide in shoreline grasses and do not venture far from those....when they do, they are zilch also.

Don't worry about stirring things up...I've been doing that all my life. You may want to go back to a thread on Crappie in which Todd Overton and I debated the merits of Gambusia. Todd was, and presumably still is, negative on Gambusia stocking, and I was positive. Look at all the data you can and make an informed decision.

I'm of the opinion that one reason that fish sellers are negative on Gambusia is that they are naturally occurring in many areas. In East Texas, you can't keep them out of your ponds, not that I would want to anyway. As a result, there isn't a big $ market for them in those naturally occurring areas.

One additional comment. My observations of stomach contents are that Gambusia are consumed by BG and small LMB. As the predators get larger, the Gambusia plays less of a role for them as forage...but they feed the BG which are then eaten by larger predators...so in effect, they help all.

Gambusia over a multi-year forage program in warmwater ponds with predators, far surpasses the FH....it isn't even close.

ML - how do you think Gambsia would fair in Nebraskas more Northern climate? I am debating whether to go with FH's or gambsia in our pond as a supplemental forage fish for the smaller BG and LMB. We do have plenty of weed cover in the pond.

Shorty,

I don't know...but to me it isn't an "either or" question as they both can serve a useful function in the food chain.

As a kid, we had a pond in Missouri and I never remember seeing a Gambusia there. You can't miss them when you walk around the shoreline.

If your fathead base is fine, I would leave it alone. My fathead base in a 2 yr. old pond is gone. I introduced Gambusia into my pond to help limit reproduction of all species, I believe it works...a little In the Spring, they are everywhere robbing nests & young. Around mid Summer their numbers peak. They are really not much for a larger fish to eat, but they seem to serve a small purpose. Some studies show they really don't have much of an effect at all in a pond.

Wow, Eastland, you have actually observed them robbing nests in 2 to 5 feet of water? Maybe we aren't talking about the same fish. The Gambusia in my ponds rarely venture more than a foot or two from shoreline where a certain death awaits those that do so. Further with their small size and lack of color, there is no way I could visually see these fish robbing nests in 2 to 5 feet of water where my BG and LMB nest. Perhaps with some elaborate equipment and very clear water, but no way in my ponds.

ML - I talked to one of our NE aqualculturists who has Gambusia available here in NE. He said that every pond he has stocked them at here in NE they have all disappeared within a year, he also said they were somewhat slow moving and easy prey for other fish. I wonder if the cooler water temps we have here every fall and winter make them easy prey with cooler temperatures. Could this be one of the reasons they do well in a southern climates but not so well in northern ones? Just a thought. His recomendations were to supplement FH's periodically instead of Gambusia for a better forage base, FH's are also a lot cheaper too.

Shorty,

I suspect it is climate related. It must be, because as I mentioned, in the pond we call Methusela (for obvious reasons) a sustained, vibrant and never stocked population of Gambusia exists.

I can't say that I have lined them both up at a starting line and yelled go...but if there were a race between a FH and a Gambusia(in my southern ponds), the Gambusia would win every time...except they never swim in a straight line.
Of course, both would be promptly eaten when they crossed into water more than a foot deep.

It is interesting that sellers charge more for Gambusia than FH's. I wonder why that is?

Gambusia appear to be very easy to raise, very prolific. Maybe its supply and demand?

Since Deb's Fish Farm is the only one that I know of on this Forum that sells and recommends them, maybe she can shed some light on the question.

Deb's Fish Farm, Kens not going to like that name.LOL

Gentlemen, I agree with Meadowlark, my pond at Zephyr is full of Gambusia and they stay in very shallow water at the shore line. The other day I was standing close to the water and a BG came skidding out on the bank chasing a Gambusia. I don't suspect the Zephyr pond has ever been stocked with Gambusia and they are really thriving. I don't have any Fatheads that I've seen

Jighead, If the fathead minnows are surviving year round in our trout pond, I would omit the Gambusia and instead stock scuds (Amphipods) Gammarus lacustrus. They will serve a better role in an ecosystem for trout.

Ooopps! According to Deb, Ken never reads the Forum so my faux pas may go undetected.

Don't worry ML I've seen Kens desk in the old cook house, he does not have e-mail he has yell-mail.

I don't know how much different it makes in survivability(sp?) but are not fatheads egg layers and Gambusias live birth. Live birth is one less step in being eaten and I think one reason Ken recommends them.

I've seen that dozens of times as well. Small LMB do the same thing to Gambusia and chase them to the dirt. It thrills my soul every time I see it.

Straight from the desk of Deb's fish farm (hee-hee)...

I have yet to have a hands on experience with the fathead minnow, but the gambusia has far exceeded the expectations of every customer of ours that has stocked them. Even our dealer in Muncie, Indiana has great success with both raising and selling gambusia. They are quick swimmers, prolific breeders, and are rather intelligent in my opinion. I say intelligent for several reasons. Any half brained fish can wander dumbfounded into open water, but the gambs appear to exhibit a higher fish IQ (funny thought) than the fatheads I have read about. Not only do they attempt to avoid predation, but they often are successful at it for awhile.

As far as the cost per lb issue I see it like this. 500 female gambusia giving live birth every 28 days or so during spawning season would be equal to or even cheaper than stocking 500 fatheads who do not survive to see a spawn. A little drastic I know... but you all are intelligent enough fish to see my point. Which fish is REALLY cheaper to stock in the long run? If you have to add fatheads every month or two... we must look at the entire forest (long term) and not just one pretty and cheap tree (short term).
I personally have yet to see harm from stocking the gambs. Quite the contrary I have seen tremendous results when stocked with the GG and other bream (also the HSB).

Speaking as a mother who gave live birth versus laying an egg out in open water(or attached to some structure making for easy prey)... heck I just have to really respect that.

Deb

BTW Ken can't even turn on a computer (or for that matter find one buried under the mountain of paperwork on his desk), but I do keep him updated on many of the threads here. His particular favorite thread goes without guessing right now. He is really proud that ML took on the TGG experiment, he actually almost jumped up when he saw the picture slideshow of the experiment (which is quite a feat for a 300 lb diabetic man), and he is really glad that a proper unbiased experiment is being done away from our hatchery/farm.

Deb, on the contrary; I generally stock about 5 lbs. of fatheads per year and they do spawn prolificly. However, the are a slow swimming, relatively shallow water fish. Neither they or their spawn last through the season. However, I have seen a school of them being chased across open water by some 8 inch catfish.

I have never seen a Gambusia. However, I like the fatties for the slow swimming, kinda chubby (protien) characteristics. I really use them to give some groceries to the smaller fish that feed the bigger guys.

I never said I saw gambusia robbing nests in 2-5 feet of water, my point was to leave a good fathead foundation in it's place. I agree with the initial post that gambusia will outcompete fatheads for survival and that gambusia will eat fathead fry. The reason gambusia were used here initially was to eliminate mosquito larve, a.k.a their alias mosquitofish, they will prey on small fry, and most small fry do originate in nests. Either way, they are only a starter food used for an initial kick-start, they will not provide a true forage foundation. Stock gambusia if you're looking to put a dent into fry reproduction.

Stepping back for a moment, taking a breath, looking at this question from a different angle.

What do FH and Gambusia primarily eat? This might help indicate if they are at all in competition with each other and might possibly indicate a preference for pond owners based on what's available in their pond.

I'll try to do the math, if I can find the average weight data for Gambusia. Live spawn every 28 days for 75 years in a pond never stocked with Gambusia and with tremendous BG and LMB fishing. Not wanting an argument, but I consider that more than an initial kick-start.

If I assumed 1 ounce per Gambusia, x numbers of spawn every 28 days for 75 years...well that would be a staggering number of pounds of free forage fish and it is the reason I like them in my ponds.

No arguement necessary. Recommending gambusia over fatheads is odd. A Gambisia live spawn every 28 days isn't bad but prior fathead research documented 4,100 eggs spawned by single female twelve times in eleven weeks (Dobie et al. 1956).

Where, in this thread, did I recommend one over the other? They both serve a useful function. One disappears in my ponds in one growing season; one has lasted for 75 years with no re-stocking or even initial stocking. I won't hesitate to use FH's again in a start-up pond; neither will I turn my back on a free resource that will over the long haul, far outproduce the FH that is already dead. What is odd about that?

I've never seen a Gambusia. They certainly don't occur naturally here. Since everything in the water eats mosquito larvae, I discount that value. Since they occur without stocking, they evidently have some manner of hitchhiking to new water. How do they do that? A pond isn't a Petri dish and I don't want to revisit "the stork brings them".

How do they stack up against Fatheads as far as size? I would assume (dangerous) that they must be faster and more maneuverable that a Fathead to escape predation. A fathead seems to tolerate a wide range of water quality. Do Gambusia also?

It sounds like, to me, that each must have a different niche and different values to the pond owner. They both reproduce heavily. Most small creatures, regardless of environment, do. There appear to be trade offs between the 2. I value fatheads because of their vulnerability to predation and spend about $40 per year on them. Pretty cheap compared to everything else relating to water and I have no idea whether they prey on tiny fry and nests like Gambusia reportedly do. It sounds like the Gambusias main value would be the offering of available fry to feed smaller predators. If a mature Gambusia is smaller and faster than a fathead, their value to anything larger than a very small predators is diminished as far as energy received versus energy expended. However, that is very important, especially to the one inch BG who also needs skinny water.

DD,

Check your e-mail for a typical Gambusia right straight out of Methusela pond...and, if you don't mind, and since I can't post it, would you please post for all to see. Thanks.

Dave,

Gambusia are very tolerant of a wide range of bad water conditions. They are real survivors, and one of the last species swimming when small ponds go bad and/or dry up.

I think gambusia is about the slowest fish in the pond. They survive by hiding, not out swimming predators. I keep hearing they eat eggs, but most beds are in water far too deep and open for them to venture into. If they even come close to LMB or BG beds, they are instant fish food.

The state of MI did some studies the determine if there was use in bringing gamusia is to help with mosquito control, and found that bluegill did a better job of keeping the mosquitos controled here. The gambusia couldn't handle the colder northern waters, and died as the waters cooled. Tried to find the study again, but could remember where I read it.

ML, I got the picture but also can't post it. It shows a 1.5 inch fish. Fatties get larger but probably not very many live to max size.

Ok, if they are both good reproducers and slow swimmers, does this indicate that fatties just don't have the survival instinct of a Gambusia?

ealong59, I think this is the study you reffered too.

http://www.michigandnr.com/PUBLICATIONS/PDFS/ifr/ifrlibra/technical/reports/2003-2tr.pdf

Here's ML's Gambusia Pic. It's what I remember ours looking like. They might have made it to 2", but that would have been a big one.

Facts from FishBase, SRAC and EFish.

There are at least 17 different species of gambusia native to the US and at least 3 more non-native ones here. Two of the non-native species are the most common and one covers the south 3/4ths of east coast area and another the Miss. drainage.

The ones I checked average 50 offspring per hatch/birth , once a month , April to Sept. That is 250-300 offspring a year. Most have a fast population doubling time 15 mths but one of the more common species has a medium population (1.4 - 4.4 yr)doubling time. There are several species which are native to small specific areas of Texas which has more different species than any other state or area. Avg. length 3-6 cm ,age 2 yrs. Food -zooplank- cladocerans , polychaetes/worms/larva , insects , bony fish (cannibal),other terrest.invertebrates. Climate - subtropical; 12 – 29°C.

Fatheads. Fast population doubling time of 15 mths. Spawns April - Aug. and average fecundity 6,803-10,164 . Age 2 yrs , length 10 cm. Food - plank.- copepods, benth. crust.- ostracods ,insects ,benthic- algae/weeds , bryozoan statoblasts, other. Climate- temperate; 0 – 33°C. Females spawn at frequent intervals, up to several times a week. A fractional spawner.

Here is a link. to some pics

http://www.fishbase.org/ComNames/ComName...5gambusia%25%27

I'm curious about the phrase "population doubling time"...can you elaborate ? It makes it sound like both species produce equivalent offspring over a 15 month period.

FishBase uses that concept and divides the fish in groups under that category . The groupings are fairly wide for example medium doubling time is a period from 1.4 to 4.4 yrs and fast is less than 15 mths. It takes into account, I think, a number of factors including fecundity , age of sexual maturity ,life span, natural morts., etc. The time it takes for a population to double. It gives a more accurate measure of a species ability to grow its population.

WOW! I am gone for 2 days and already three pages!

Just to clarify, i believe that the fish that i am referring to is the Gambusia Affinis, also know as the western mosquito fish. I am sorry if i caused confusion because i didnt clarify.


The main issues/concerns that i have with introducing gambusia are:

1. Do Gambusia Minnows eat Fathead minnow eggs/fry?

2. If they DO is it a significant amount?

3. Do Gambusia Minnows and Fathead minnows compete for the same spawning grounds, and food.

4. Would have been about spawning numbers, but thanks to Ewest and several others that has already been resolved.

Right now I am leaning towards not stocking gambusias and instead revamping my Fathead minnow spawning structure.


Thanks - Jighead

Bill Cody,

I truly like your idea of adding scuds to my pond. As i flyfish frequently for trout, i realize the importance of scuds in a trouts ecosystem and diet. In fact, i believe that the importance is even greater to a pond trout than it is to a stream trout.
The first time I ever actually thought about introducing a substantial population was when i read your post.

So naturally i have a few questions:

1. Is there a easy way to get a supply of them?

2. It is very possible for me to culture them in large tanks, then seine them out into my pond. Is it best to buy a small population and then culture a large population before introducing them into my pond? Or are they prolific enough that they do not need my help?


Thanks for the excellent idea, I am excited about starting my own population.


- Jighead

Jighead :

I hope I did not confuse things for you. Sometimes info can do that. With a trout pond I would do what Bill suggests.

Look at this link about your questions.Then open # 2 from the list.

http://www.scirus.com/srsapp/search?q=%2...mem=jnl#results

Ewest, as usual, thanks for the info.

Jighead, Check out ColoradoFisheries.com. They should be able to help you and provide answers to your questions about scuds for trout. Please keep us advised about your progress with scuds (Gammarus lacustris). If you have a fair amount of shallow water weed beds the scuds should do quite well for you. If you have a small secluded pond with no fish in it or just minnows you could develop a population that produces a constant supply of scuds.

I wouldn't worry about gambusia and fatheads competing for spawning areas. Gambusia are live-bearers, and don't need spawning areas.

GAMs have major survival advantages over FHM that are directly related to reproduction.

GAMs breed "on the fly". They mate while swimming and when inseminated, the female GAM can produce multiple broods without further matings. They are vulnerable during the act of mating only for a few seconds.

GAMs don't lay eggs. The only way for the eggs to be lost is for the female to be eaten. Though fecundity is lower, have much better survival of critical brooders.

FHM minnows spawn. Males are the critical brooders. They protect the eggs. Males are vulnerable to predators while protecting their nest. When the males are gone, there is no more reproduction.

FHM minnows need spawning habitat.

They eat different things and FHM are better to have but if the forage must reproduce the GAMs will do better. In any pond still supporting FHM reproduction, however, GAMs probably should be avoided.

My pond is just over 2 years old. The number of fish I've personally stocked will barely cover the bottom of a 5 gallon bucket.

Thanks to hurricane Harvey, I've got both GAMs and what I think are Rosie Red FHM (Their tales are red anyway). Both have survived naturally against a swarm of different predators, tho the GAMs far outnumber the the reds.

The GSF tend to spawn in inches of water right against the bank and I watch them religiously. Can't say I've ever seen either species ever get brave enough to venture into a guarded nest. However, once those fry are self motivated to leave home, I have no doubt their survival rate is affected by both GAMs and FHM, but only initially. Gape for both minnows is very limiting as to what they can swallow.

I will say this tho, both are very adept at feeding on pellets. Especially when its hydrated first. They come running as fast as they can when I ring the dinner bell.