Pond Boss Forums GENERAL QUESTIONS Water chemistry Bream of all sizes dying

Recently (past week)have been having bream of all sizes dying in my pond, approx. 10 or more per day. Have 3 yr. old catfish in pond also but none dead. Pond is aereated with diffuser 24/7. Had water tested and PH is 7.8, Alkalinity 50 ppm, calcium hardness 130 ppm. Any suggestions?

Have you been able to inspect the fish and perhaps notice sores or even a blueish film on them? I've witnessed bluegill only die-offs around my parts during the early spring (which is later than yours!). Sometimes, bacterial or protozoal infections can just plague one species. You will usually see external signs like I mentioned, but not always. I see this in the early spring and think it might be related to continual fluctuations with water temps. This can induce stress which makes infections more liekly.

See these 2 threads from the archives

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=92486#Post92486 Fish Kills



http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=92438#Post92438 Fish Diseases

Looks like the most likely suspect is temp change. I'm in north FL and last Sat. temp was 80, next day was low 50's. Sounds like an oxygen problem. No lesions on fish, just dead!Thanks for a;ll input.

With aeration going, I wouldn't suspect oxygen. Also, oxygen usually hits larger fish first and your cats don't seem to have a problem.

Rapid water temp changes can kill fish even if O2 is high. If they can't regulate their intercellular changes quick enough then its lights out. That is my bet if its not an external source.

Here is the info.

Cold Tolerance and Fatty Acid Composition of

Striped Bass, White Bass, and Their Hybrids

ANITA M. KELLY*1 AND CHRISTOPHER C. KOHLER



The dynamics of lipid composition of cells occurs in order to maintain a constant fluid matrix for enzymes associated with membranes (Greene and Selivonchick 1990). 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 6.5C (Satoh et al. 1984). Viola et al. (1988) demonstrated that the common carp Cyprinus carpio, which is capable of mobilizing lipids from muscular and visceral deposits, is able to survive to 4.5C under the same conditions.



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.



Physiologically, fish are affected by variations in water temperature in two ways (Hochachka and Somero 1984). 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 (Hazel 1993). 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 20 d in some species (Doudoroff 1942; Brett 1944). The rate of resistance to lower temperatures is governed in part by the rate of metabolism, which is depressed at lower environmental temperatures. 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 (Johnston and Roots 1964; Caldwell and Vernberg 1970; Hazel 1979; Cossins and Prosser 1982).

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 (Greene and Selivonchick 1990). 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.






Fish deaths due to cold temperatures have frequently been reported. It is generally believed that deaths arise from the rapidity of dropping temperatures whereby the fish are unable to acclimate to the lower temperature despite being within their biokinetic range.

So, if rapid water temp change is the cause of the problem, will all the fish die? We are continuing to find at least a dozen or so dead each day of all sizes and now have lost 4 large catfish. Buzzards starting to hang around.

Valarie,

How deep is our pond, and what is the approximate average depth?

Deepest part of the pond is 18ft, with an average of 7 or 8 ft.

A little worried about this myself (I'm a worry wart) but it's forecast to be 60 tomorrow during the day, then 20's and blustery tomorrow night....hoping for the best.

Me too, took out 6 fully grown cats today along with several bream. All fish sem to be dying.

I went down to the pond today and found about a dozen or so bream dead also. my pond is also 18ft deep and averages about 8ft. I just stocked 800 5" bluegill two weeks ago. I really don't want to watch them all die. I hope i don't find anymore dead tommorow. this could have something to do with why the fish haven;t been feeding well even with the warm temps.

Let's commiserate all together. I took out three dead RES and one BG today. They appeared to have been dead for some time, so I am wondering how long corpses will keep floating up.

Last night I thought I had a dead bluegill. I guess it was just playing possum. It was half out of the water, laying in the mud at the edge of the pond. I nudged it with the end of my fishing rod, and it took off for deep water.

Are all my fish gonna die?

I would leave off the aerator when a cold front is gonna come thru. That will leave the shallows to warm even on coolish days. I doubt an O2 problem this early in the year unless you have high biomass.
Listen to me, with the FA I am starting to have, I would have started the aerator, but the little compressor is DOA. It has been 80s the least few days, but with cooler weather coming, I am glad it is broken or I would have probably turned it on and left town.

These may be delayed winter kill fish... A lot of times fish survive the immediate stress of winter low DO levels, but as the water warms and their metabolisms speed up, the stress of winter catches up to them and they die.

Couple of BG, one GC and one little FHM are the only floaters so far, tomorrow might be a different story. It's so cold out, my big bad bird dogs don't even want to go out tonight. 60 degrees when I woke up this morning, 26 degrees right now.