Pond Boss Forums INTRO Questions & Observations Tilapia Die-Off?

I know most of you are doubtful, but try veggies. Just throw (chumming) a bunch of floating veggies everyday before regular feeding and the tilapia will start to eat. None of the rest of the fish will. Then in a few days try floating a small piece of cabbage on a number 6 or 8 hook in the chum and I think you will be pleasantly surprised. I like floating because I have no patience, the dough things works well for me also, but also attracts cats and carp.
I know it's not too macho to say you caught "this lunker on Belgian Endive", but canned biscuits? just the trans fatty acids alone......

Todd the hsb seem to be growing at a constant rate and are fat but the largest one I have caught is probably four pounds and thats only in two years. I am assuming that it is one of the original stockers I got from you when I drove to your farm two years ago. Todd in order to keep a constant line of hsb going in the pipeline how often would you reccomend stocking new fish. Also in my opinion the tilapia are an excellent substitute for the shad. My hybrids are constantly feeding on them. They chase schools of them into shore and devour them and there never seems to be a shortage of new tilapia in the 2-3 inch range. Their reproduction rate is unbelievable but what happens in the winter? Last year I just quit putting out pellets because nothing was eating them. Thanks Todd for the tip on the biscuit dough I will give it a try on Friday. I bet it will work on catfish also.

James,

George has been restocking with 50 fish every year in a 2+ acre pond with and seems satisfied. Restocking density probably depends more on how much you fish in the summer and whether you lose those fish caught during the summer. Also base your restocking density on the numbers removed. Restocking 10-15 fish per acre per year seems like it makes most sense for most people.

If your HSBs aren't eating pellets during the winter then don't worry about that, just make sure that they get groceries when the water temp is right...60-80 degree water represents good growing conditions.

Hope this helps you.

I have become a huge fan of tilapia and would recommend them to anyone wanting to increase their forage base, clean out unwanted plants and have something nice for dinner. My season is now over for the tilapia. They began to die last week but once again the other fish in the pond benefitted from them. Instead of just all of a sudden dieing they started to act like a wounded bait fish. This triggered a huge feeding frenzy of almost all of the predators in the pond. I caught a few fish Sunday and every one of them looked like they had a yoke sac underneath them. I believe this will really help them over the winter almost like a bear that gains weight before hibernation. Does anyone else have a similar story? Has anyone had any negative effects from stocking tilapia?

I'm still confused on Talapia die off. When the water temps drop, they die. I got that part. But what happens to there bodies? Do the other fish eat them when they are dead? or do they float around until bird, racoon or something else comes along to eat them?

The fear I have is that I'll have hundreds, or thousands of these fish floating on the surface of my water.

Thanks,
Eddie

Eddie, that vast conglomeration of dead Tilapia just doesn't seem to occur. In ponds with predators, before the Tilapia die they get sluggish and become very easy prey. And ML has reported that even in his Tilapia-stocked pond with no predators, he didn't see a lot of dead fish - "Mother Nature's Cleanup Crew" of coyotes, raccoons, etc. took care of business.

Note: That was before ML lived at the Ranch and was out there as a weekender, IIRC. So maybe it takes a few days for the cleanup crew; I bet the Tilapia dieoff is spread out in time enough that the cleanup crew can eat them over several days without much or any buildup.

-Theo "If I lived in Texas I'd be using Tilapia already" Gallus

I wrote last year about water temperature tendencies based on clarity. We continue to see tilapia in clear water surviving weeks after tilapia in muddy or planktonic waters die first.

May we all welcome tilapia dying season?

At 55F to 53F when tilapia get sluggish the predators of LMB, HSB and maybe catfish are still fairly active. They no doubt eat lots of the smaller tilapia daily. IMO the complete stomach evacuation rate for LMB and HSB at 55F would not be much longer than 24 hrs. Ewest may be able to verify this with a reference.

Bill IIRC at 55 LMB metabolism is just starting to slow but the winter prep eating binge is in full swing so they can add lots of fat for winter. That is why with winter temps at 50-55 the LMB in SoCal and central/south Fla are so big and fat - the gorging process continues unabated most of the winter. I would think that HSB do the same but keep the eating process going to a lower temp. I will find a thread where the winter prep process in discussed.

Here is the thread :

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=7;t=000315;p=1

Here is the ref. :

Transactions of the American Fisheries Society 111:549-558, 1982

Energy Partitioning in Largemouth Bass under Conditions of
Seasonally Fluctuating Prey Availability

S. MARSHALL ADAMS , R. B. McLEAN, AND J. A. PARROTTA

ALL OF THE FISH THAT i CAUGHT ON SUNDAY WERE TOTALLY GORGED WITH TILAPIA. I JUST DON'T UNDERSTAND WHY THEY CONTINUED TO FEED WHEN THEIR STOMACHS WERE ALREADY SO FULL OF TILAPIA. I DIDN'T SEE ANY TILAPIA FLOATING OR ON THE SHORE BUT I DID SOME THAT ACTED LIKE THEY WERE STUNNED AND UNABLE TO SWIM PROPERLY. THIS IS MY THIRD YEAR OF TILAPIA AND i HAVEN'T SEEN ANY NEGATIVE EFFECTS OF HAVING THEM ONLY POSITIVE.

I haven't seen my tilapia in a month. They are in my "bass on feed" pond so that high number of bass I'm sure are doing some cleaning but there are some larger ones in there. I thought on the warmer days I would see them in the shallows.

Saturday, while I was fishing, I took water temps in the shallows, it was 51 degrees. I spotted several Tilapia in the shallows, they appeared ok and submerged as I approached.

I don't know what the deep water temps are, the jon boat is "high & dry" due to the drought...5-6 ft. low. I didn't want to make too much noise dragging the boat to water, I was Duck/Deer hunting too Ponds are great ! I saw what appeared to be 2 Hooded Merganser's that were worthy of mounting...just couldn't get them within range...adding water to my property has produced 10 fold in return if not more...

We had a sunny warm day today here in central Texas. I have been looking for my dying tilapia because I don't have near enough predators to eat mine. I saw the strangest thing. There were a couple of dozen tilapia of all sizes near the surface barely able to move and they were covered in mud. The mud was patchy on all sides. I wonder if the ground is warmer than the water, would they try to bury themselves? Any one else ever see this?

That's really interesting. I've seen bluegill that looked like that. They got so cold that they laid on the bottom and got mud on them, then they recovered enough to swim for a while. I also wonder if what looked like mud could have been a dark colored fungus, which I've also seen a couple of times. ML, have you seen this?

Ever wonder why some fish have higher cold lethal temp. (tilapia) than others (YP). The following is some info on why. A note to understanding this is that fish that have a diet of more carbs (plants) instead of fats (lipids) fish oil , dye at a higher cold lethal temp. In this study the prepared diet (pellets) was higher in carbs and less lipids than the natural diet.

The rapid onset of cold temperatures
has been reported as the cause of death
in several species of fish . It is believed that
the lipid composition in the fish muscle plays a
vital role in the ability of fish to adapt from one temperature to another .
Phospholipids are the class of lipids in which the most obvious changes occur. As environmental
temperatures decrease, the invariable response is
an increase in fatty acid unsaturation . Conversely, as ambient temperatures increase, phospholipid saturation must also increase to avoid excess fluidity. The dynamics of lipid composition of cells occurs in order to maintain a constant fluid matrix for
enzymes associated with membranes. Different species of fish differ in their patterns of fat deposition and mobilization, which in turn affects the temperature range in which the species can grow and survive. For example,
the Nile tilapia Oreochromis niloticus does
not store excess lipids in the musculature but rather relies on visceral deposits that it is incapable of mobilizing at low temperatures, which results in high mortalities between 8C and 6.58C. Viola et al. demonstrated that the
common carp Cyprinus carpio, which is capable
of mobilizing lipids from muscular and visceral
deposits, is able to survive to 4.58C under the same conditions.
Diets influence the fatty acid composition in several species of fish , and the ability of a
fish to alter its lipid composition when placed in colder water is one factor that determines survival. For example, summer harvest syndrome is an anomaly seen in goldfish Carassius auratus when they are harvested in the summer and placed in tanks containing water that is colder than the pond water. The death of these fish is thought to be a result of the fat that the goldfish consume or produce . Goldfish with high concentrations of saturated body fat are less tolerant of temperature change than fish with high concentrations of unsaturated body fat. Similarly, rainbow trout Oncorhynhcus mykiss that have been fed diets high in saturated fats stiffen and die when placed in cold water (Mitchell 1990). In these fish, the fat
apparently hardens in the colder water, causing the fat-impregnated muscles to stiffen and the fish to become exhausted and lose movement.
Although it has been hypothesized that temperature is closely linked to membrane composition, relatively few studies have been conducted to determine if a correlation exists between lipid composition and cold tolerance. This study was designed to determine the effect of a sudden temperature change (a simulated cold front) on fish fed either a natural or prepared diet, as well as to determine their lower incipient lethal temperature. The association
of fatty acid composition and unsaturated:
saturated fatty acid ratios in these fish were
examined with respect to their tolerance to cold.

We demonstrated that diet-induced muscle fatty
acid composition directly affects cold tolerance . Fish fed fathead minnows had U : S fatty acid ratios 10–25% higher than fish fed a prepared diet. When subjected to a simulated cold front, all groups of fish fed the prepared diet suffered high mortality (50–90%) whereas the groups fed the natural diet experienced zero mortalities. The LILT was also higher for fish fed the prepared diet. The amount of unsaturated fatty acids in the muscle is believed to affect a fish’s ability to tolerate lower temperatures. In general, the tissue temperature of fish is within 18C of the ambient water temperature. Physiologically, fish are affected by variations in water temperature in two
ways . First, temperature determines the rate of chemical reactions, and secondly, temperature dictates the point of equilibrium between the formation and disruption of the macromolecular structures in biological membranes. Structural flexibility, therefore, is a requirement for integrity of biological membranes . Cold temperatures constrain this flexibility and, as a result, stabilize less active conformations.
The rate of increase in the ability of
fish to tolerate higher temperatures usually requires less than 24 h at temperatures above 20C, whereas the gain in resistance to lower temperatures is a much slower process, requiring up to 20d in some species .
The rate of resistance to lower temperatures is governed in part by the rate of metabolism, which is depressed at lower environmental temperatures. The simulated cold front in this study resulted in higher mortalities . Although no studies have been conducted to determine the amount of time required to gain resistance to lower temperatures , this study suggests that when these fish receive a natural diet they are well suited to sudden changes in water temperature. However, when these fish are
fed a prepared diet, this ability to adapt to sudden decreases in water temperature is less apparent. This suggests that diet influences the fish’s ability to adapt to sudden water changes.

Pondmeister Bruce was right again. I was able to catch one of the muddy fish that was belly-up this morning. These fish were covered with a slimy goo that had mud stuck too the goo. Here are a couple of photos:

Yep, that's definitely a stress fungus. It looks like every dead hybrid striped bass I've ever found in my ponds after ice-out. Yuk. :p I'll bet someone like Bill Cody even knows what type of fungus it is.

I have found a couple of dead LMB that looked like that over the last 3 years. I always figured whatever it was grew on them after they died.

You learn something every day at Pond Boss.

Very interesting. There are at least three analogous conditions in humans. One is “subcutaneous fat necrosis of the newborn.” The second is chilblains of the thigh. The former occurs when newborns are exposed to cold temperatures, especially after stressful deliveries. Neonates have highly saturated fat, especially high in stearic and palmitic acids, and it is likely that these are denatured under these circumstances.

Chilblains are especially common in environments where the thighs are exposed to wet cold, e.g., Great Britain. (The condition is almost never seen in Alabama.) I once saw a very nice presentation on the topic in England. There, females who exercised horses in winter, wearing tight lycra pants to do so, got chilblains, whereas males who wore loose-fitting jodhpurs did not.

Sclerema neonatorum is a fortunately rare condition in newborns usually associated with serious underlying disease. It is usually fatal and shows crystallization of their highly saturated subcutaneous fat.

Has anyone observed the abdominal fat of any species of Tilapia to see if the fat shows signs of crystallization or necrosis? Anyone in academics who has access to Tilapia suffering cold stress and can take specimens from them might have an easy and highly publishable paper.
Lou