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#489680 - 05/07/18 01:59 PM Fish mortality for a pond amateur...
KapHn8d Offline


Registered: 10/02/17
Posts: 140
Loc: TX
Howdy, y'all!

My first pond mini-pond went in last fall (around Oct). I filled it with well water, which I suspect was anoxic coming out of the ground. I bought a Vertex PondLyfe 2 system and installed before filling... kicked it on as soon as I could and it's been running ever since (24/7). After a few weeks of churning, I bought a few fish (about 1.5lbs FHM, ~24 CNBG, ~8 RES) I live in east Texas and the winters are mild. I checked temps a few times during the winter and the lowest I saw was low 50's, so I never turned off the aeration. The fish did great all winter and are still doing fine (for the most part). I lost a minnow or two over the last 6 months and figure that is just normal. Nature has found it's way to the pond... crawfish holes along the bank, crows showing up on my game cam with wiggling fresh-caught minnows in their mouth (I didn't know crows fished), a redear slider moved in and a common snapper visited for a couple weeks before moving on, etc.

Today, the water temp is 82 degrees and the fish are still eating well (I hand feed Aquamax), but I found a bluegill lethargic near the bank... not gasping, so just sitting there not swimming. I reached down and turned it around and it slowly swam off. I walked around the pond and found another bluegill dead. These are the first sunfish deaths since I stocked them 6 months ago. I've been hoping to see some bluegill fry, but haven't yet. There are a lot of minnows that have spawned and the fathead fry along the banks are copious. I have been hoping to find an albino channel catfish to add to the pond, but no luck yet. There aren't any predator fish AFAIK... at least I haven't added any yet.

My question for you Pondmeisters - Is there an expected or regular fish mortality rate that is considered normal? I mean, living fish have to die as some point and lots of things can cause that... if I find single dead fish and another looking suspiciously not normal, should that be a red flag or should I chalk it up to coincidence? I don't currently own a way to test the pH, so that is still an unknown, but all other visual queues I know to check appear normal. Aquatic plant growth (outside microorganisms) is virtually non-existent due to the newness of the pond. Any pointers?

I'm still learning all the time and appreciate y'alls' patience with my level of ignorance.



Thanks!
/clayton
_________________________
96.85840735 percent clayton... the rest is just pi.

We become what we think about.

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#489684 - 05/07/18 02:11 PM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
AquaticsFanatic Offline


Registered: 05/07/18
Posts: 19
Loc: Indiana
It sounds like to me that there was some toxic elements that came from your well water. It is definitely not normal to find dead fish especially if you are finding them regularly something is happening to them. I have been managing a 1 acre pond for 6 years now and stocked it heavily the first 3 years and have been stocking it heavily with bait fish ever since and I have never not a single time found a dead fish. Fish obviously do die but it shouldn’t be happening regularly the fish in the pond should be getting eaten by other fish long before it just dies IMO. That being said it doesn’t mean that your source of water isn’t the end of the world if you have no other options you can probably still manage a decent BOW. Maybe consider adding catfish to help clean up the fish that can’t take the toxins. Over time the fish that can handle the toxins well will breed and produce more fish that are likely to be less susceptible to the toxins in the water. Ideally getting a new source or aerating your water before it goes in the pond to help remove harmful toxins would be the best option but if not you can make do with what you have if need be.

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#489685 - 05/07/18 02:16 PM Re: Fish mortality for a pond amateur... [Re: AquaticsFanatic]
KapHn8d Offline


Registered: 10/02/17
Posts: 140
Loc: TX
Thanks for the response.

For clarification, the aeration system turned the well water for almost a month before fish were added and that was 6 months ago. Since, any compensation for evaporation has been from rain water and water shed. I've only added well water again once, it wasn't much, and it wasn't recently.

You not finding any dead fish in 6 years is an interesting data point for me though... thank you. I'm sure I'll get this dialed in over time. I just wanted some experienced thoughts on what I was seeing.

Cheers!
/c
_________________________
96.85840735 percent clayton... the rest is just pi.

We become what we think about.

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#489687 - 05/07/18 03:07 PM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
AquaticsFanatic Offline


Registered: 05/07/18
Posts: 19
Loc: Indiana
I’ve fished many bodies of water where dead fish were visibly present so I’m not saying it doesn’t happen, but there is always a cause. Sometimes pollution, sometimes a hard freeze, aeration or oxygen/carbon dioxide levels,, overheating, choking trying to eat a fish or bird that was too big lol etc..

I’m def no expert but start with getting your water tested. And not just for the basic PH, alkalinity, salinity, ammonia, nitrates, nitrites, etc.. you might send it into a lab to get a full analysis on what’s happening bc you shouldn’t be seeing fish just die off regularly.

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#489693 - 05/07/18 03:57 PM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
Quarter Acre Offline


Registered: 06/10/16
Posts: 469
Loc: West Central Missouri
As mentioned, water quality is always suspect.

Your fish looks pretty healthy, I assume it is a dead one? It's tail fin looks a bit ragged, but not bad at all. Nothing to suggest cause of death.

I'm new to all this as well...82 degree water temps sounds high especially this early in the year, but what do I know about Texas norms? Should you be looking into just aerating at night? I know that the goal is to turn the pond over at least once a day, but can it be turned over too much? The Pondlyfe 2 system should be turning you small pond over many times a day. At what depth is your diffuser"?

Could these loses have something to do with spawning. I know in the aquarium world attitudes of breeding/parenting fish can change quickly and have some casualties. Not to mention the stress of not eating during the spawn.

Just my thoughts...I wouldn't worry too much about a few fish showing up dead or weak, but it is a good steward to be concerned.
_________________________
Fish on!,
Noel


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#489694 - 05/07/18 03:58 PM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
ewest Offline
Moderator
Hall of Fame 2014

Lunker

Registered: 03/08/05
Posts: 19286
Loc: Miss.
Yes there is a natural mortality (Morts) rate and it is very high. Obviously most BG are eaten while still very small (fry) and this effects the rate. With a life span of only a few years many die early. Were all the dead fish in good condition ? I often see a few dead BG just after the first major spawn but they usually look rough (not like the pic above). I will check but IIRC second year morts are in the 15 to 20% range.
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#489696 - 05/07/18 04:19 PM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
KapHn8d Offline


Registered: 10/02/17
Posts: 140
Loc: TX
Thank you for the guidance, fellas... I do sincerely appreciate it.

The answer to the question about the membrane diffusor location(s) is they are on the bottom at the deepest point (which is only about 7 feet).

The water temp was taken about a foot and a half below the surface. I just assumed that with all the circulation in the pond, the temp would be uniform within a few degrees. I can certainly check it deeper, farther from the sun so to speak.

Thanks again for taking a moment to respond and share some wisdom.

/c
_________________________
96.85840735 percent clayton... the rest is just pi.

We become what we think about.

Top
#489698 - 05/07/18 05:09 PM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
Quarter Acre Offline


Registered: 06/10/16
Posts: 469
Loc: West Central Missouri
I would also assume that the temps would be consistent throughout the water column, my question is...is 82 degrees too warm?

And, can your diffusers be set higher in the water column so that there is a thermocline that allows for a cooler water reprieve? I doubt that is really possible in such a small pond with that size of an aerator system. Only running the aerator at night could keep the pond's temps lower and your air system is certainly large enough that it does not need to run 24/7.

I'm looking forward to some expert details here, I'll keep tuned as I will be aerating this summer and could use some more lessons.
_________________________
Fish on!,
Noel


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#489749 - 05/08/18 11:34 AM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
ewest Offline
Moderator
Hall of Fame 2014

Lunker

Registered: 03/08/05
Posts: 19286
Loc: Miss.
82 F is perfect for LMB and BG etc. Fast changes in water temp at any level can be a problem. Fish eating a high % of pellets as their diet are a little more susceptible to fast water temp change problems (at the margin). Not a big problem and not necessarily all pellet types. Natural food (fish , plankton , ect) insure the right lipid balance which is key to fish handling fast temp changes.


Edited by ewest (05/08/18 11:40 AM)
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#489750 - 05/08/18 11:54 AM Re: Fish mortality for a pond amateur... [Re: ewest]
Acoursey Offline


Registered: 10/26/17
Posts: 40
Loc: West Lafayette, IN
Originally Posted By: ewest
82 F is perfect for LMB and BG etc. Fast changes in water temp at any level can be a problem. Fish eating a high % of pellets as their diet are a little more susceptible to fast water temp change problems (at the margin). Not a big problem and not necessarily all pellet types. Natural food (fish , plankton , ect) insure the right lipid balance which is key to fish handling fast temp changes.


Could you please explain regarding lipid balance and handling temp changes?

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#489757 - 05/08/18 01:50 PM Re: Fish mortality for a pond amateur... [Re: KapHn8d]
ewest Offline
Moderator
Hall of Fame 2014

Lunker

Registered: 03/08/05
Posts: 19286
Loc: Miss.
This is at the extreme margin of relevancy for pond owners and is simply passing on info in that context. If you are feeding BG , HSB or LMB (carnivores) as opposed to CC , carp , tilapia or shads etc (omnivores or herbivores) then lipids from fish or natural diets (eaten) provide the ideal lipid structure for rapid temp (cold water) change survival. Pellets do not provided that as well as natural foods except that pellets with substantial quality fish meal in high % come close to providing that. Here is some text from a study about the matter using HSB. Same concept for other similar fish.

Cold Tolerance and Fatty Acid Composition of
Striped Bass, White Bass, and Their Hybrids
ANITA M. KELLY*1 AND CHRISTOPHER C. KOHLER

Fish fed the prepared diet also died at higher temperatures
than fish fed the natural diet (Figure 1).
Striped bass fed the prepared diet had the highest
lower incipient lethal temperature (LILT; 5.98C),
followed by palmetto bass (4.88C), sunshine bass
(2.58C), and white bass (1.98C). Fish fed the natural
diet had considerably lower LILT, with all taxa
being near 0.08C, except palmetto bass, which had
a LILT of 1.88C. Palmetto bass was the only taxon
in which disease became a problem at lower temperatures.

The phospholipid fatty acid composition
for the muscle lipids for all four taxa were reflective
of the diets they received (i.e., the natural diet
had a higher percentage of unsaturated fatty acids,
as did the muscle tissue of the fish that consumed
the natural diet;

We demonstrated that diet-induced muscle fatty
acid composition directly affects cold tolerance of
striped bass, white bass, and their hybrids. 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.

Diets influence the fatty acid composition in several
species of fish (Henderson and Tocher 1987;
Lovell 1989; Seo et al. 1994), 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
(Mitchell 1990). The death of these fish is thought
to be a result of the fat that the goldfish consume
or produce (Mitchell 1990). 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.
The amount of unsaturated fatty acids in the
muscle is believed to affect a fish’s ability to tolerate
lower temperatures (Hoar and Dorchester
1949; Hoar and Cottle 1952a, 1952b). In general,
the tissue temperature of fish is within 18C of the
ambient water temperature (Carey et al. 1971;
Reynolds et al. 1976). 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 208C,
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.
The simulated cold front in this study resulted in
higher mortalities in the striped bass and the palmetto
bass when compared with the white bass
and the sunshine bass. Although no studies have
been conducted to determine the amount of time
required to gain resistance to lower temperatures
in striped bass, white bass, or their hybrids, 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.


Edited by ewest (05/08/18 02:12 PM)
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