Pond Boss Forums INTRO Questions & Observations Mozambique Tilapia Dying

I've recently renovated my pond to include underwater aeration, plant life and some minor restructuring around the edge (grading, bogs, etc.)

I've had Largemouth Bass & Bluegill in the pond from day 1. After a few days since the completion of the pond, a few more Bass, Bluegill and Mozambique Tilapia were introduced, all from the same fish farm source.

I'm in South Florida, so water temperature isn't a issue. However, most of the 15 Mozambique Tiliapia have died within the past 7 days. Several of the Bluegills had as well. The die off has tapered off the past few days, but I did have one Mozambique floating on the surface tonight.

I've since added my own Bluegill that I caught locally a few days ago and they seem to be thriving as well as the Largemouth Bass that were introduced 7 days ago with the original Bluegill and Tilapia.

The water was tested before the pond work and just the other day. Everything looks near perfect in all categories. Other than possible stress, I can't figure out why the Mozambiques are dying.

The only other thing I can think of, but not much of a issue at all now, we had some minor dredge/grade work done on the sides of the pond. That caused a lot of mud and silt to be stirred up. We ran the underwater aeration for a few days before adding the fish and it's really cleared up tremendously and settled back down.

Is it possible the Mozambiques gills could not handle some of the stirred up silt/mud? With it being settled now, is it worth trying another batch? The only other fish in the pond besides the Bass & Bluegill are some walking catfish that have always been in the pond. None that I expect to be a serious threat to the good sized Tilapia.

My pond is about 1/8-1/4 acre and about 10 feet deep in the middle. It has very little duckweed on the surface in small patches, which used to be bad before the aeration and fountain and some other grass/algae in spots, but overall very clean and nice looking. It has two man made shallow bogs with water plants.

Thanks

What do the tilapia look like? Any signs of disease, stress or physical damage?

Did you just turn you aerator on? If so did you turn it on gradually or all at once?

The Tilapia looked pretty good when they were placed into the pond. Within a day, they looked stressed.

Cody, the aerators were turned on at once and left on for about a week before the fish were introduced. For the first few days, they were left on 24/7, then shut off for a day. Then back on during daylight hours via timer, which they are still at now.

big ph swing from source to your pond? big temp swing (even a 5 deg difference is big for tilapia)?
while they are pretty hardy and can handle a lot, i've read that sudden changes can really stress them

I doubt it was the turbidity as they are very hardy. Did any of the LMB die?

I don't think it was oxygen related since the LMB and bluegill weren't affected. You were lucky you didn't kill everything though, when you turned on your aeration system and just let it run 24/7. The pond must have already turned over and de-stratified. In the future, if the aeration system is ever turned off for a week or more, make sure you start it gradually. If you are going to run it on a timer, it is better to run it at night rather than during the day. When the sun is out, photosynthesis occurs, raising DO levels. At night, oxygen is consumed, so your lowest DO levels would be first thing in the morning.

Thank you for the responses!

The Largemouth Bass that were put in are all fine. They are actively cruising around the edges for minnows and small bait fish, making for some explosive moments. The Tilapia were all large, so were not targeted by the Bass.

Some of the Bluegill died, but those looked stressed. The ones that lived and the ones that I put in from a local lake all seem to be thriving.

The pond company we used did turn on the aeration gradually from what I was told and it was ran at night during the first couple of days.

I'm not very knowledgeable yet with the water conditions of pond care, but I do know the company tested it before it started work and after. Indicating the water was in great shape.

They are replacing the Tilapia and advised that if it wasn't stressed their guess was that the fine silt that may have not settled all the way down, may have affected their gills more than the other fish.

I do know that before a couple died, they did look very stressed - dull color, swimming slowing and gradually leaning to side and the fins looked sickly.

As far as a 5 degree temp change, that is possible. The day they were put in, a cool front moved through. However, a South Florida cool front means it went from 80s to 70s during the day and 70s to 60s at night (air temp) for a couple days.

The walking catfish have been in the pond since before we got here, when it was a tiny hole of still water. They are all thriving still too.

I think walking catfish are so cool! I had one show up on my back portch one evening when it was raining. I had no idea what it was until I did a little research. I put it in one of my fishtanks that evening and early the next morning I heard my husband go down stairs and scream. The catfish had gotten out of the tank and was in our foyer. My husband thought it was dead and when he went to pick it up it was very much still alive. They are native to Asia, but do exist and thrive here in South Florida. Where are you located?

" ...advised that if it wasn't stressed their guess was that the fine silt that may have not settled all the way down, may have affected their gills more than the other fish."

I don't believe that sand or silt would cause any problem with tilapia. They filter feed bottom detritus and silt all the time for food. Stocking stress is my guess.

I'm hoping it was just stress. The new batch of replacement Tilapia should be coming next week.

Sue, I was originally in Weston, but now in northern Palm Beach.

Mcp...not to rain on your parade, but only blue tilapia are legal in florida....all others are banned, even from possession.

First I've heard of that. I called the pond builder & the company they used here in Florida for the fish and was assured everything was fine. I guess I could ask them for Blue's since the others died.

MCP...Florida gets real serious about their tilapia control...only Blue Tilapia are the only legal live species allowed in Florida, and ONLY in the southern half of the state. No live tilapia species of any kind is allowed to be possessed or even transported through the northern half of Florida.

In the grand scheme of things in florida...the DNR there has a picture of a NILE tilapia on the website as an example of what a BLUE tilapia looks like....I have pointed that little mistake out to them...the state biologist says it is a Blue....oh well.

Res, so are the Tilapia supposed to be boated to S. Florida or flown??

No one seems to know (or care) about permits. Generally speaking, if there are no stops other than food or fuel in a direct route to a (legal) destination, non-hazardous cargo can move through a state unimpeded.

That was why I didn't get ticketed in Nebraska least spring.

The Tilapia that were stocked in my pond came from a farm about 30 minutes from where I live. They came in the back of a pick up truck in a tub. Definitely no long haul.

I'm beginning to wonder if they were actually Blue Tilapia and the pond builder called them Mozambique's. I'd find it hard to believe that a reputable builder is getting illegal species of Tilapia from a local Tilapia farm. Hopefully that is the case.