Tilapia Diseases 101

Tilapia tolerate adverse water quality and other stressors better than most other commercial aquaculture species. Because stress and environmental quality play such important roles in the disease process, tilapia are labeled as being very "disease-resistant." This basically means that in the presence of pathogens, tilapia are the last to break with disease.
As a result, tilapia growers worldwide did not historically practice clean culture methods. Moreover, they did not generally implement the biosecurity measures that had become standard in industries that grew less disease-resistant fish such as trout and salmon. In other words, there was no apparent penalty for being careless - or so it seemed.


Read more:  http://www.americulture.com/Disease.htm

When fish are sick I generally add enough salt to bring the concentration up to 3.0 ppt.
While the fish stores may try to sell you various cures, my experience is if it takes anything more than salt your fish were probably doomed to die anyway. 

Some people go higher then 3.0 ppt, but that's what I use.  I have a meter so it's pretty easy to be accurate but you can go by weight.  For example if you have a 100 gallon system you will add about 2.5 lb of salt.  I did a little math.  5.5 cups = 2.5 lb.

So get some plain Solar water softener salt and dump in 5.5 cups for each 100 gallons of water in your system.  Toss it in the sump tank so as not to hurt the fish.  You can change out some water to bring the level down to about 1ppt after the fish stop dieing.  You should not leave the salt that high forever because it's not good for some plants and the pathogens you wish to get rid of can adapt to the high salinity, but a little is good.  I like to use Sea-90 to keep trace minerals in the system.. You could use Sea-90 instead of Solar water softener salt, but it's more expensive.

Green house pest management

Green house pest management can be an overwhelming problem; especially in an aquaponic system.   But these fungi are not limited to soil less gardens or greenhouses.



5427594
I'd like to thank Forestry Images for thier wonderfully helpful site.
With great photos to help identify various problems,  microscopic slides and petri dish samples they have made identification much simpler.

Pythium diseases
brown spot
Phytophthora blight Fusarium wilt
blue mold   powdery mildew leaf scorch sour rot
white ear rot and seedling blight of maize bitter rot and anthracnose

Jon Parr and Vlad are some of the best contributors to the aquaponic  forums.
Here's a little advice they have pasted on that I appreciate.

Link to discussion

GH (Green House) pest management has three strategies, and which is best is really open for debate.
1- intentionally low pest security, meaning wide open large screens for honey bees, pests, and pest predators. This works pretty good for lazy folks like myself, especially if you are planting beneficial plants to attract the predators. No fuss about pollination, and no big concern about sterilizing everything.
2- moderate pest security. This one is fine for new greenhouses, and light traffic GH's with cleanly guests. Once a pest gets inside, though, trouble trouble.
3- high security, meaning positive pressure and HEPA filters, thrips screening, humidity and temp control, haz-mat suits and dissinfect routines. Just the thought of all that work spoils my mood, but is probably the smartest long term plan for commercial use.

I'm a low security type guy. Address the pest directly. Mold? Increase airflow and temp, decrease humidity. Spider mites, fungus gnats, white flies, aphids? Allow predators, spray with tea, nuke them with CO2. Nasturtiums are awesome for the garden by the way; trap crop or aphids, pest predator magnets, repel white fly and spider mites. Yep. And borage, and multicropping.

 Vlad Jovanovic
Link to discussion.

You can use the 'ol 3-5% oil + 0.5% dish washing detergent remedy...works well but you have to be real careful to get as little of the concoction into your system and take measure to cover up your FT to protect from overspray. And even this low % of oil will burn pepper plants if you have any...won't damage them beyond repair or anything, just don't be freaked out by the necrotic lesions that will be left on their leaves. peppers seem especially sensitive to this type of treatment.
A better/easier/more fish safe bet might be a naturally occurring fungus called Beauvaria bassiana that will take care of a whole host of common garden pests...spider mites included (and then some). B. bassiana can be purchased under the trade names Botaniguard, Naturalis-L or Mycotrol-O the later two being ok'd by OMRI...and more importantly it is fish safe (unlike any kind of oils or most soaps).
Whatever you spray with make sure to repeat after 3 or 4 days...then again after 3 or 4 days...and then once more...since most of these sprays wont kill the eggs that they've laid...so make sure you get the bastards that have hatched...and spray the under-sides of the leaves...Good luck. Spider mites are a royal PITA.

Here is a link to another in depth discussion about Botrytis cineria and Sclerotinia sclerotiorum
Botrytis blight 
Sclerotinia rot

Pythium

I have been plagued with Pythium when starting new seeds and this information presented by Nick Savidov may just help me and find the cure.

This is a very good scientific study of aquaponics,  I highly recommend looking at it.