Pond Boss Forums INTRO Questions & Observations Tilapia Mating Habits

As I tell my wife about birds "it's hard to tell if they are fighting or ....... mating. The same seems to be true with fish. I was watching the tilapia and they would get nose to nose and bump and then one would back up fast. The other one would go nuts and swim around and act crazy. I'm sure that must be the male. Anyway, looks like tilapia mating season is in full bloom.

Yep, especially true of Tilapia. The nice thing is that once it starts, it never stops all season long...and all those little offspring, the ones that survive also begin mating in a couple of months...eating algae and feeding your predators. Tilapia, what a great fish!

If you have or are interested in tilapia you should read this link for facts.

From --- http://srac.tamu.edu/tmppdfs/11830457-283fs.pdf

Tilapia
Life History and Biology

Reproduction

In all Oreochromis species the male excavates a nest in the pond bottom (generally in water shallower than 3 feet) and mates with several females. After a short mating ritual the female spawns in the nest (about two to four eggs per gram of brood female), the male fertilizes the eggs, and she then holds and incubates the eggs in her mouth (buccal cavity) until they hatch. Fry remain in the female's mouth through yolk sac absorption and often seek refuge in her mouth for several days after they begin to feed. Sexual maturity in tilapia is a function of age, size and environmental conditions. The Mozambique tilapia reaches sexual maturity at a smaller size and younger age than the Nile and Blue tilapias. Tilapia populations in large lakes mature at a later age and larger size than the same species raised in small farm ponds. For example, the Nile tilapia matures at about 10 to 12 months and 3/4 to 1 pound (350 to 500 grams) in several East African lakes. Under good growth conditions this same species will reach sexual maturity in farm ponds at an age of 5 to 6 months and 5 to 7 ounces (150 to 200 grams). When growth is slow, sexual maturity in Nile tilapia is delayed a month or two but stunted fish may spawn at a weight of less than 1 ounce (20 grams). Under good growing conditions in ponds, the Mozambique tilapia may reach sexual maturity in as little as 3 months of age, when they seldom weigh more than 2 to 4 ounces (60 to 100 grams). In poorly fertilized ponds sexually mature Mozambique tilapia may be as small as 1/2 ounce(15 grams).

Here are all of the SRAC tilapia fact sheets:

Tilapia Production

SRAC 280 Pond Culture of Tilapia
SRAC 281 Cage Culture of Tilapia
SRAC 282 Tank Culture of Tilapia
SRAC 283 Tilapia: Life History and Biology

http://srac.tamu.edu/index.cfm?catid=11

OOOOHHH! I want some! Great fish.

So I wonder with east Texas climate and assuming mature Talapia are stocked in mid April minor bloom,no feeding,..........how many generations can we expect before they shut down in cooler water tempertures?

If we call the inital stocking first generation, then my guess would be lots of third generation fish and possibly some fourth generation by the die-out time. However, they stop reproducing below 68 degrees and that happens considerably in advance of the die-off in East Texas.

In my first season with Tilapia several years ago, I stocked some in a pond without predators, just for fun. At the die-off, there were hundreds of 3,4 and 5 inch fish...zero small ones and zero large ones. The die-off happened Christmas time, but reproduction must have shut down much earlier as indicated by the complete absence of fry.

Here is my guess. Incubation ranges from 20-22 days, and maturation of ova takes two weeks. Fry are released in shallow waters by females once they have reached a length of 9-10 mm. Adults will spawn within 10 days of going into pond assuming temps ok. Assume adults are used.

April 15 -- adult fish put in
April 25 -- first spawn
May 25 ---- first brood released
June 10 ---- second spawn
July 10 ---- second brood released
July 25 --- third spawn
Aug 25 ---- third brood released
Sept 10 ---- fourth spawn
Oct 10 --- fourth brood released
Oct 25 ---- to late for another batch

EWEST,

I think I answered a different question? My answer (guess) was based on "how many generations":

First generation: April 1 (original stockers)
Second Generation: May 1 (spawned by original stockers)
Third generation: August 1 (spawned by second generation fish)
Fourth generation: Oct. 1 , (spawned by third generation fish) .

I agree with you that the original stockers(first generation fish) will spawn four times, possibly even five, but my guess was relative to generations. The second generation fish will spawn three possibly four times, the third generation once and possibly twice, but not likely more.

This year, I believe my first spawn was well before May 1. It is very possible I will see a fifth generation fry spawned by a fourth generation fish. Put all this together in a tree structure and one can see that you end up with thousands and thousands of fish...just what we want!

ML :

I started to address the pyramid effect but did not do so as it gets to complicated. Because the different sets of offspring mature differently and start spawning at different times and on different schedules you get a pyramid of spawning not the linear method I set out for generation one. I would not guess at how many different generations you would have from all the offspring as I am not sure what a generation is ( example grandkids are same generation no matter which offspring they came from) and with only a 30-38 day reproduction gap it would be real hard to figure out. Almost like a constant rolling spawn with fry of every age, depending on conditions.

How come it's the males that have to swim around and act stupid?

Okay, for all you "long hairs" out there, I made some rough calculations based on assumptions that show the numbers of Tilapia fry per acre produced for forage consumption is at least 2 billion and much more likely upwards of 27 billion in our East Texas climate.

Here's how I arrived at those very conservative numbers:


From SRAC, Tilapia spawn numbers are 2 to 4 eggs per gram of weight. Assuming the middle number of eggs become fry (3 eggs), assuming a female surviving stocking rate of 5 pounds per acre, this equates to 6811 fry per acre. Assuming those females, let�s call them first generation, all spawn four times (very reasonable) equates to 27244 fry. You also have to factor in weight gains of the females, which means more eggs and more fry. For this, I�m going to very conservatively estimate a four-fold weight gain. Hence, the original, first generation fish will result in about 109,000 fry total per acre�but as we will see, this is miniscule in comparison to the multiplying effects of succeeding generations.

The final result we are after is how many fry per acre result from an initial "surviving" stocking rate of 10 pounds per acre (half of which are assumed to be female). Now this is where it starts to get interesting�. in order to establish a range on the final result, assume that 60% to 90% of the fry are eaten by predators before they can reproduce themselves. The first 6811 fry, then will result in 2724 to 681 survivors and assuming 50% females 1362 to 340 Tilapia that will be reproducers. Let�s call them second generation. The second generation will spawn three times beginning when they are about 3 ounces in weight producing 4,170,168 to 1,041,012 fry. Likewise, assuming the third generation spawns twice which results in 212.8 million to 13.2 million fry. Now further assume the fourth generation spawns once resulting in 27 billion to 1.7 billion fry per acre available for forage�add in, if you want, the other generations but they are actually masked by the last spawn.

It should be obvious, even in spite of math errors and/or differing assumptions that Tilapia reproduction is stupendous and that by the end of the season, the amount of forage that is being generated per acre is flat awesome.

Two questions:
How can they grow so much in a season if they spawn so many times and then have fry in their mouths all summer?
How can you catch small tilapia? I put some adults in a 30'X 60' hole. I've been told that they are hard to seine and then some of you said that they don't go into traps. Has anyone tried to cast net them? I hope that they are not to smart for that.

ML - Based on the calculations, I may be able to walk all the way accross my pond by stepping on Tilapia.

Heybud,

More likely you can walk across the pond on the backs of those LMB fattened up by Tilapia...what a fish that Tilapia!

Dangit I want some too!!

they rock and can be caught on a fly rod

ML has lost his mind ! It reminds me of the saying, "it must be true, I saw it on TV !"

If I'm wrong, ML has figured out how to eliminate world hunger

BrianH,
I have an uninvited neighbor that does quite well with a cast net and it seems that the tilapia never learn. Even with his success the tilapia thrived until I finally placed enough cover to limit his casting area. The real damage he di was when he could no longer net the larger fish he started on the fingerlings. That and the introduction of a predator at the same time just about wiped them out.
There must be other control factors, the ponds in my area are stocked with tilapia yet are never over run, in fact barbs usually out number them. Many of these ponds do not have predators. I have seen fingerlings chase fry and I have seen adults eating fry that are feeding on pellets and other surface food.

Why thank you EL, that is the nicest thing you have ever said about me...and I can say that in all honesty.

More on this topic from someone who "has lost his mind". The following is copied directly from the SRC publication:

Growth and yields
in aquaculture
Under good growth conditions,
1-gram fish are cultured in nursery
ponds to 1 to 2 ounces (20 to 40
grams) in 5 to 8 weeks and then
restocked into growout ponds. In
monosex growout ponds under
good temperature regimes, males
generally reach a weight of 1/2
pound (200 + grams) in 3 to 4
months, 1 pound (400 + grams) in
5 to 6 months, and 1.5 pounds (700
grams) in 8 to 9 months. To produce
1-pound (400- to 500-gram) fish,
common practice is to stock 6,000 to
8,000 males per acre in static water
ponds with aeration or 20,000 to
28,000 males per acre where 20 percent
daily water exchange is economically
practical. After 6 months
of feeding with good quality feeds,
such ponds can produce 5,000 to
7,000 pounds per acre and 18,000 to
20,000 pounds per acre, respectively."

Producing 20,000 pounds per acre every 6 months would seem to feed a lot of folks. Do the math yourself, and very probably mine contained mistakes because I did it in my "lost" mind. Wonder why commercial ponds only use unisex Tilapia?

As an example, if those 20,000 pounds were all female and at a reproduction rate of 3 fry per ounce of female weight, do the math for a multiple spawn cycle without predation....the numbers are staggering, absolutely staggering.

I'm sure I made math errors in my "quick and dirty" analysis and the results certainly indicate some of the assumptions may be questionable, but most reasonable people can look at the raw numbers and agree that Tilapia forage production is flat awesome.

From the same series of SRAC fact sheets. Recall that these are about aquaculture not recreational ponds and forage. The reasons are to prevent overpopulation and stunting , because males grow about twice as females and no wasted energy/investment from mating.


Species such as Tilapia zilli, T. hornorum, or T. mossambica are not suitable for mixed-sex culture because they reproduce at an age of 2
to 3 months and at an unmarketable size of 30 grams or less.Two to three crops of fish can be produced annually in the tropics
compared to only one crop in temperate regions.
Fish farming strategies that prevent overcrowding and stunting include:1) cage farming where eggs fall through the mesh to the pond bottom before the female can collect them for brooding; 2) polyculture with a predator fish, such as fingerling largemouth bass, at 400 per acre; and 3) culture of only males(monosex). All-male culture is desirable in ponds not only to prevent overpopulation and stunting but also because males grow about twice as females.

Male monosex culture.
Males are used for monosex culture because male tilapia grow faster than females. Females use considerable energy in egg production and do not eat when they are incubating eggs. Male monosex culture permits the use of longer culture periods,higher stocking rates and fingerlings of any age. High stocking densities reduce individual growth rates, but yields per unit area are greater. If the growing season can be extended,
it should be possible to produce fish weighing one pound (454 grams) or more.

The rates and numbers and weight gains in these papers should be viewed in the context as written wrt aquaculture operations not recreational ponds unless so specified in the article.

EWEST,

I'm having trouble understanding exactly what you and EL are disputing about my post.

I started the above quote with the heading from SRC "Growth and yields in aquaculture". Was that misleading?

I concluded that "It should be obvious, even in spite of math errors and/or differing assumptions that Tilapia reproduction is stupendous and that by the end of the season, the amount of forage that is being generated per acre is flat awesome."

Perhaps words like "stupendous" and "flat awesome" are less than precise and perhaps non-scientific, but I think most everyone understood their meaning...and I repeat, most reasonable people would agree that indeed Tilapia are flat awesome forage producers.

ML:

I understood your post on potential Tilapia reproduction to show the approximate potential numbers that could be produced through multiple generations of spawning. And you applied a Fudge Factor to attempt to account for fry loss through predation, which makes your numbers (much) more realistic than those classic, simple Fibonacci Sequences showing that the mass from the offspring of a single pair of rabbits will exceed that of the Earth in (2 years?).

We could all discuss the amount and timing of numbers reductions in real world Tilapia populations, well, pretty much forever (all one has to do to end the discussion is to completely understand every aspect of a pond ecology - no trivial task), but it would not affect your basic point that ... (DRUMROLL) ...

TILAPIA PRODUCE A WHOLE LOT OF OFFSPRING!

ML :

I am providing info to the forum as a whole not disputing anything. You asked why the male only approach in the articles and I answered as per the fact sheets. My reason for posting the info is to encourage others who don't know how all this fits together to go and read the fact sheets and other posts here and material elsewhere to get informed. Learning is the key. Everyone here should , but many don't , know the differences between aquaculture operations and recreational ponds. That is stressed in my post because it is important so others will have a context in which to read , both the post and understand the fact sheets.

For example this text from my post,

"Species such as Tilapia zilli, T. hornorum, or T. mossambica are not suitable for mixed-sex culture because they reproduce at an age of 2
to 3 months and at an unmarketable size of 30 grams or less."

is directly from the fact sheet, is correct in the aquaculture context, but the conclusion "are not suitable for mixed-sex culture " is dead wrong in the pond context. Why -- because the goals are opposite. In the aquaculture setting the goal is quick growth to eating size while in the pond context it is many offspring of the proper forage size for the predator fish. Further the fact sheets jump around between aquaculture points and methods and can be confusing. The reader has to stop and think about what is written and see if the point has positive or negative application to a recreational pond. There are both types of points made in the fact sheets (some are good for ponds some are not).

Tilapia are strong forage producers as are BG , FH , Tshad and others. They each have their own characteristics which can be positive , negative or neutral depending on the situation. Forum members need to know or learn about all of this so they can make wise choices.

I will say that tilapia are being grown worldwide in aquaculture operations in an attempt to feed the world or at least provide some protein. I do think the fisheries biologists and organizations who are doing so are smart and will use their efforts and resources on the best fish and methods that are available to them to try and feed those in need.

I trust this will clear up my purpose and methods. My goal in posting had nothing to do with your writing style or your opinion or points about tilapia.

Theo you make my point well -- in the fact sheets male only method they make NO offspring (nor are they wanted) while in the pond they make lots (and are the purpose).

Give a man a fish, and he is fed for a day.
Teach a man to fish, and he is fed for a lifetime
Teach a man to raise tilapia, and forgedaboutit.