Pond Boss Forums INTRO Questions & Observations Does aeration make tilapia less effective?

I added a Vertex Air 1 plus to my pond early this week from Ted Lea (who was very helpful, BTW) and am contemplating how effective the tilapia will be given the lower water temps in the upper layer of the pond now. Last week, surface temps were in the low 80s which is perfect for the tilapia. Since aeration was added it's now in the low 70s. Does anyone have any experiences for comparison? Maybe the aeration benefits counteract the tilapia's slightly lower metabolism? I don't have a source for the tilapia yet but I'm working on it.

Since FA grows on the bottom, and aeration would increase the temperature down there, maybe it makes the Tilapia MORE effective??? Where (what depth) do Tilapia spend most of their time?

Interesting question, Ryan. Climate conditions are very different here in East Texas and aeration does not appear to have any significant effect on surface water temps durng the summer months and no effect at all that I can discern on Tilapia.

I would guess that you will see a steady-state surface water temp much higher in a few days when the water mixing reaches a kind of equilibrium. Shallow water warms quickly and since Tilapia seem to hang out in water depths of 5 feet or less in my ponds, the effect should be minimal...but I'm just guessing. For sure, Tilapia are super sensitive to declining water temps.

In the 2006 stocking, the tilapia only ate algae down to about 3 feet in May and June, making a very distinct line that I assume was due to temp. I had a pretty good bloom in June and couldn't see deeper than 2' for most of the rest of the summer. The Algae growing deeper was minimal (not fouling a hook much) and really didn't bother me because I couldn't see it. What little made it to the top didn't last long.

The water was noticeably clearer yesterday (the third and longest day of aeration so far) so I'm guessing this will allow plants to grow even deeper especially with the improved deeper water quality. Side-thought: Maybe time for some dye? I was a bit surpised by the clearing water. I had somewhat expected the water to cloud up due to the clay and any muck being stirred up. Maybe the clearing is due to dilution of the plankonic algae mixing with the rest of water column? In 2006 with no aeration the rate of tilapia stocked seemed just adequate, meaning a little algae would appear and in a couple of days be gone. I'm I correct in thinking that FA will likely grow deeper now = more area for it to grow? = stock more tilapia than before?

This problem has now become actual as opposed to theoretical. I have been offered 20 female as well as 2 male tilapia that are 10+". I am picking them up on Thursday. The generous donor is interested in the results and my only obligation is to attempt to retrieve them this fall with their help. I would like to get them to spawn but I fear they will not since the water is about 72 degrees right now so I am considering two options. #1 Turn off the brand new aeration system completely, #2 Only operate the system periodically from 9PM to 9AM. My problem with option 1 is that I wouldn't be getting any of the benefits from aeration. I'm not sure if opt#2 will actually be enough time for the water temp. to rise into the 80s if there is no aeration for 12hrs per day. Will the fluctuating temperatures in opt#2 keep the tilapia from spawning even if it does reach appropriate temps?

Reproduction of Oreochromis niloticus niloticus

Main Ref: Trewavas, E., 1983
Mode: dioecism
Fertilization: external
Spawning frequency: no obvious seasonal peak
Batch spawner: Ref. Trewavas, E., 1983
Reproductive guild: bearers
External brooders
Description of life cycle and mating behavior: Sexual maturity is reached at 3-6 months depending on temperature, reaching about 30 g. Reproduction occurs only when temperatures are over 20�C. Several yearly spawnings every 30 days. Females incubate eggs inside their mouths (approximately for a week) where larvae hatch and remain until the vitellus is reabsorved.Egg size 1.5 mm, larval length at hatching 4 mm. Spawns in firm sand in water from 0.6 to 2 m deep of lakes. Males set up and defend territory which are visited by the females. Courtship lasts several hours. Eggs are shed in batches in shallow nest and fertilized by male. Each batch of eggs is picked up into oral cavity by female. Females solely involved in broodcare. Female carries up to 200 eggs in her mouth where the larvae hatch and remain until after the yolk-sac is absorbed.

Reproduction of Oreochromis aureus

Main Ref: Trewavas, E., 1983
Mode: dioecism
Fertilization: external
Spawning frequency: one clear seasonal peak per year
Batch spawner: Ref.
Reproductive guild: bearers
External brooders
Description of life cycle and mating behavior: Nesting usually in shallow water weedy areas (Ref. 96). Males establish territory and dig a spawning pit (Ref. 2, 6465, 54601), using mouth and fins (Ref. 2), up to 60cm deep and 4-6m in diameter; a number of territories can often be found clustered together (Ref. 52307). Territories are defended by means of agressive behaviour (Ref. 6465), including lateral display, lateral biting and mouth-to-mouth combat (Ref. 2). Reproduction is stimulated by long photoperiods and inhibited by short daylengths (Ref. 54365). Reproduction requires a minimum temperature of about 20�C (Ref. 2). Males visit schools of females and attempt to attract a female spawning partner (Ref. 2, 52307). Courting behaviour in the nest consists of lateral display by both sexes with nipping and tail-flapping (Ref. 2). Eggs are deposited in single clutches, from several dozen to 100 eggs (Ref. 52307), and are taken into the females mouth as soon as they are fertilized (Ref. 2, 6465, 52307), with a peak spawning frequency around the 9-11th hour of light (Ref. 31140, 54365). One female may hold up to 2000 eggs in her mouth (Ref. 2). The female swims away to deeper water with the brood after spawning is complete (Ref. 2, 52307), while the male renews spawning activities with another female. Hatching occurs about 3 days after oviposition (Ref. 2). Incubation time varies with temperature, 13-14 days at 25-27�C (Ref. 2, 52307) or 8-10 days at 29�C (Ref. 144), and juveniles leave the mother's mouth when they are about 1.1cm in length (Ref. 54601). The young school near parent's head for a few days, reentering the mouth at any sign of danger or at a gesture of the female; parent-offspring relationship ceases after 5 days (Ref. 2).


Reproduction is best at water tem-
peratures higher than 80o F and does
not occur below 68o F. In subtropical
regions with a cool season, the num-
ber of fry produced will decrease
when daily water temperature aver-
ages less than 75o F. After 16- to 20-
day spawning cycles with 1/2-pound
Nile tilapia, fry recovery was about
600 fry per female brooder at a water
temperature of 82o F, but only 250
fry per female at 75o F.

It turns out my fears were based on poor data. My $8 thermometer was wrong, imagine that! It turns out my temps measured 85.8 F for at least the first 2', +/- .4 degrees in various locations, yesterday around 7PM which is just about perfect.

This is one great thread. I've learned a lot. Thanks to all. Ryan, will you periodically post the depth line that they eat the FA? I'm wondering if the aeration will make a difference. Or if temp makes a difference. Or if deeper FA is yucky tasting to tilapia.

Ryan, glad you discovered the thermometer problem as this would be the only time I have had water temps that cool in a non spring fed pond.With our 96F temp yesterday surface temps in the 70's would be difficult. Let us know how it goes and remember you have a regulator installed on that unit to slow things down when / if needed.

+1. My surface temp was 85.5F last night at sundown.

I'll keep updating, probably here http://www.pondboss.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=5;t=000421;p=8 since it's sort of a continuation of that project, unless the moderators would like me post somewhere else. I've got a good bloom at the moment so visibility is less than 2'. These tilapia will have a head start on last years, basically beginning with a clean pond due to a somewhat risky Cutrine treatment last week. We'll see if they can maintain until this fall and clean off the limestone rip-rap.

Thanks Ryan. Either place would be good. Just glad you are updating and raising new questions.