Fish Stories: The aqua in aquaponics
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Transcript of Fish Stories: The aqua in aquaponics
The Aquatic Component
● Fish and other species suited for the system– (covered in Class One, but slides are
appended)● Habitat needs● Water quality issues● Fish biology (too big a subject for this class)
– Will cover some basics of fish diseases and salt.● Food needs and sources● Fish growth rates
Habitat● Solitary fish often
need lots of places to hide, and most fish will be less stressed if they can hide part of the time.
● Hides can include plant life, big rocks, wood and PVC pipe.
● Schooling fish tend to need more room.● Some fish, like catfish, need a substantial
amount of horizontal room in order to breed.
© dailymail.co.uk
Water Quality issues - Important tank parameters
● pH● Temp● Nitrogen● Mineral hardness● Oxygen● Chemicals
– Chlorine/chloramine/metals etc.
Chemical Tests
© Jethro Hanson
© Bootsy on the BYAP forum
PH scale
From WikipediaLog scale
Tap water pH: it changes with age● When water comes out of the tap, it's usually
very poorly oxygenated and high in carbon dioxide (CO
2). The carbon dioxide forms a weak
acid, so the pH of the water will be artificially low.
● As the water ages, the CO2 outgases, and
therefore the pH rises (gets more alkaline).● When you first start, test the pH of the water
right out of the tap, then age it a few days and test it again.
pH, cont...● Shoot for a neutral (7) pH.● It's a good balance between fish, plant and
bacteria requirements.● High or low pH will affect what can grow in the
system, and how the plants take up nutrients.● Having said that, I know of systems that run as
low at 6.0 and as high as 8.0● Lemon juice (acid) lowers pH, Baking Soda
(base) raises it.
pH, cont...● Adding shells [or other Calcium Carbonate
(CaCO3)] to the system will buffer the pH to
the mid 7's, and is a common way to control pH.
● As a bonus, the shells will add micronutrients.
● The bacteria will tend to lower the pH over time.
● Always adjust pH SLOWLY.● Fast changes in pH kill fish.
pH vs Nutrient Uptake
Temperature
● The temp of the water affects how much oxygen it can hold – the warmer the water, the less oxygen.
● The temp of the water affects how the fish deal with nitrogen, especially Ammonia.
● All fish have a comfortable range.● Some fish need specific temps to breed.
Temp, cont...
● Lots of docs talk about celsius. Easy to convert online.
● In google search, type “convert 4f to c” and it will give you the answer.
© Harriet P.http://goscandinavia.about.com/od/weatherinscandinavia/qt/tempconversion.htm
The Nitrogen Cycle
© Backyard Aquaponics Magazine, vol 1
● It's all about the bacteria:
● Nitrosomonas sp.
– NH4 → NO
2
● Nitrobacter sp.
– NO2 → NO
3
Bacteria● Like to live on a surface● Reproduce rapidly● Need good oxygen levels in the water● “As a general rule, a brand new system will take about 4
weeks to cycle at around 68*F.● Colder temps take longer.● Dryness and temps above 120*F kill the bacteria, as does
freezing.● Nitrosomnas sp likes pH 7.8 – 8.0● Nitrobacter sp. Likes pH 7.3-7.5
Info from Backyard Harvest Magazine, vol. 1
Nitrogen: Ammonia (NH4)
● Fish excrete ammonia, but ammonia is toxic to fish.● Damages tissues, esp. gills and kidney● Impairs growth● Decreases resistance to disease● Can kill.
● Also produced by excess food and dead fish.● Toxicity depends on water pH and
temperature.
Nitrogen: Ammonia (NH4)
The warmer the temperature, and the higher the pH, the more toxic the ammonia.
● Less toxic than ammonia, but can still kill● Stops fish from absorbing oxygen● Toxicity can be controlled with salt (more later)
Nitrate (NO3)
● One of the major plant nutrients● A level of 0 means the plants are using it all● Safe levels are about 0 - 40
Nitrite (NO2)
Mineral hardness (hard water)● Hard water is water that has high mineral
content (mainly calcium and magnesium ions, but sometimes others).
● Two types of hardness:– alkalinity (often referred to as carbonate or
temporary hardness)– permanent hardness
From BYAP forum, “water hardness and fish health”and http://en.wikipedia.org/wiki/Water_hardness
Alkalinity● Not the same thing as high pH!● Alkalinity refers to the hardness derived mainly
from carbonate and bicarbonate ions and directly reflects the buffering capacity of the water.
● This form of hardness is also called carbonate hardness or temporary hardness because it can be precipitated and removed by boiling the water. Which is why lime-scale forms in kettles and showerheads!
Permanent Hardness
● Permanent hardness measures the ions such as nitrates, sulphates, and chlorides etc, that are not removed by boiling.
● Most of these are not involved with buffering but can affect pH values.
© http://www.ceasa.co.in
Hardness, cont...
● As a rule of thumb, hard water is usually well buffered while soft water is usually less well buffered.
● This can be inaccurate, depending on conditions.
● Water tests are available for both types of hardness.
● Hardness is another good reason to put sea shells in your system (or grit, egg shells etc.)
Oxygen● Fish, plant root and bacteria all need decent O
2
levels.– Flood and drain through gravel or substrate– Water falling– Aerators
● Fish O2 needs vary
● Tests are available.
Chemical Contaminants● Chlorine and Chloramine
– Added by municipalities– Get rid of it by adding drops
● From pet store, or bulk sodium thiosulphate (ebay)● http://www.cnykoi.com/calculators/calcstdose.asp
– Chlorine can be aerated out of water, chloramine can not (mostly)
© Foster and Smith
Other contaminants
● Copper is harmful to some fish and fatal to crustaceans.
● Some drops can also neutralize heavy metals.● When all else fails, go to a reverse osmosis
filter. Very very expensive, but does the job.● (Doctors Foster and Smith sells RO for $100 –
$500, depending.● http://www.drsfostersmith.com
Fish Diseases
● For the most part, fish medications are not safe for humans to eat.
● Do not medicate fish while in an AP system– Put the fish in quarantine
● If you want to eat the fish, the main treatment is salt.
● High concentrations of salt should also be used only in a quarantine system.
Fish diseases● Ammonia/nitrite poisoning● Temp issues● Bacterial infections
● Includes fin and tail rot● Fungal infections● Parasites
● Internal– Hole in head disease
● External– Ich or whitespot– Gill flukes
© Foster and Smith
© JBL - Online Hospital
© my-tropical-fish.com
© aquariacentral.com
Hole in Head disease
Ich (whitespot)
Finrot
http://www.drsfostersmith.com/pic/article.cfm?c=3578&articleid=1338&category=583
Salt, the AP cure-all● Helps against nitrite toxicity● Reduces fish stress (helps with
osmotic pressure)● Killing off parasites (ich)● Short, strong salt dips/baths can
help healing wounds or parasites (also common practice with new fish before introducing them into general population)
© API
Salt, cont...
● Use sea salt or sun-dried salt.● Sea salt also contains lots of micronutrients
● Do NOT used iodized salt, or salt with other additives to make it a pellet or anything.
● Solar water softener salt is cheap and easy to get in big bags.
● Pool salt from pool supply stores will also work.
When to use salt
● Some people have salt in their systems all of the time, up to about 3 ppt (parts per thousand)
● Higher concentrations can be used for short dips or baths to treat fish with injuries.
● Salt will kill some plants– Strawberries die at very low concentrations of
salt, but most plants are OK up to about 3ppt.
How much salt?
● Salt concentrations are measured in parts per thousand (ppt).
● 1 kilogram (kg) of salt in 1000 liters of water = 1ppt.
● That comes out to about 1/3 lb of salt for every 40 gals of water.
● Or 3.8 grams of salt into 1 gal of H20 = 1ppt
Fish food
● As always, needs differ. Some fish are carnivorous (trout, barramundi), omnivorous (tilapia, catfish) and herbivorous (plant nibblers and grazing fish, like plecos).
© funfishtanks.com
Fish food sources
● Nutritional needs differ, but all fish need a balanced diet. You can't live on weeds alone.
● To start, it's probably best to go with a commercial food.
– I now buy mine in 50lb bags, which last me about a year.
● Grow your own:– Vermicomposting worms, black soldier fly
larvae, other insects (hang a bug zapper above the tank?), duckweed, other plant matter.
Fish Growth rates
● This is usually discussed as “Feed Conversion ratio” or “Feed efficiency.”
● For instance, tilapia are often quoted as having a rate of roughly 1 : 1.5
– with a feed conversion ratio of 1.5, the fish would gain 10 grams for every 15 grams of feed
● Will depend on feeding frequency, type of food, water conditions and other factors.
Questions?
Resources● JBL Online Fish Hospital
● http://www.jbl.de/?lang=en● Good fish health search, via picture or text
● http://www.byapmagazine.com● Backyard Aquaponics magazine. Good, well-written, thorough articles.
First Edition is free.
● The collection of “Useful Information” articles on BYAP:● http://www.backyardaquaponics.com/forum/viewforum.php?f=11
● Water Hardness and Fish Health● Salting for Fish Health● Ammonia – The Silent Killer● etc.
Resources, cont...
● Doctors Foster and Smith● Good online store, good selection, good articles
and is in Wisconsin, so less shipping distance.● http://www.drsfostersmith.com
● Aquatic Ecosystems● Another good online store, tends to be a bit more
industrial than Foster and Smith● http://www.aquiaticeco.com
Resources, cont...● Miami Aquaculture
● Online source for tilapia. Mixed sex and all-male fingerlings, only in bulk, but breeders available individually
● Multiple breeds of tilaia, including the hybrid Rocky Mountain White, which is cold(er) hardy.
● http://www.miami-aquaculture.com● R&D Aquafarms, Inc.
● All-male tilapia fingerlings available in small batches. In Oshkosh, WI.
● http://www.rdaquafarms.com
Fish!● A critter that lives in water that produces
ammonia or other source of nutrient.● Common:
– Tilapia– Perch– catfish
● Cool!– snails (be careful of the pump)– Crawdads/crayfish/yabbies/redclaw– Shrimp, mussels, eels, other.
● Ornamentals– koi, tropical fish
Photo © BYAP
Fish considerations
● Ease of care● What do they eat?● What temperature water do they require?● Are there special water requirements?
– pH, salinity, hardness● Rate of growth / efficiency of food -> growth
conversion● Are they tasty, my precious?● Do you enjoy them?
● Most people start with goldfish – cheap, hard to kill, eat anything.
● Once you get a feel for the system and how it works, expand to a fish more suitable to your conditions.
● Do you want to heat a tank all winter?● Do you want to grow fish out to eating size in 9
months?● Are they legal in your state? (tilapia are illegal in
some southern states).● Native, local fish are often a good choice.
Be prepared to become a Be prepared to become a serial fish killerserial fish killer
Photo ©Joel Malcolm & BYAP