Backyard Aquaponics
A place to discuss aquaponics

Thanks for the heads up. The tank they went into has plenty of algae etc. around the edges they seem to be enjoying anyway. They are so cute... I just love going out and watching them swim around. What a treat. It's been a very long wait and the poor plants in the greenhouse have made me want to avoid it. But soon...

Victoria,

They should love the algae and it will absorb some ammonia.

Tempting to have a friend bring some down here when she comes to visit her father, but I think I want all males right now.



Jaymie,

Is this SOP (fasting a few days) true for tilapia in particular or simply SOP for fish in general?

I fed mine within hours and all was fine, but I did keep a close eye on them and ammonia/nitrites. Tilapia are darned tough ("piscine rats" ), but I am new at this and may simply have been lucky. I also had them in an aquarium so I could really, really see them well...if there were any problems....or pleading for food! And I am never good at waiting...or following directions...or respecting the voice of experience...or ignoring begging. I'm a baaaad boy. *sigh*

I don't know what my results would have been with the normal settling-in fast. I have heard on this forum that, with tilapia at least, initial growth determines their long-term growth trajectory. This would be an interesting experiment if someone will run a side-by-side test, but it might vary with stress the fish have undergone and other factors: you might get great results or lose them all. I'm sure SOP is safer.

All this said, mine were far smaller that these when I received them and I had several times that mass of fish already in the aquarium and still had an ammonia/nitrite spike for a few days.

So what you are really saying is... feed at your own risk or should I say the risk of creating HSM...

I have never waited to feed fish added to my tanks Fish splash in, followed by food. They mostly take it.

I have to confess I'd fed them twice before Jaymie said I shouldn't and they ate a whole lot of duckweed yesterday. This morning ammonia, nitrites & nitrates all still 0. I'd love to see some nitrates so will keep edging upwards.

Tilapia will tolerate conditions that would kill most other fish,,,almost bullet-proof.
Remember VERY small sized pellets( 45-50% protein),,,10% bodyweight feeding split over 3 feeds per day (AFTER Bacteria has had a chance to catch up). Scale backto 5% body weight and30% protein when about4 inches long.

Thanks for the info, Chappo. Sounds like we are right on. There are a number of people locally who grow trout so the local feed store carries fish chow and looks like what we got is good for now. We've also had to special order the feed they'll need later since trout have a higher protein requirement for grow out. Looking at the specs on that, it looks good too. And, knowing the size to switch finishes the info.

Victoria- How are your fish now? Do you grow both trout and Tilapia?
Did you find a way to keep your greenhouse warmer?

HB

Sorry, it's been a long time since we've updated. We only have tilapia and they are doing great. We found a home for many of them with a person from Tacoma and Tom's brother-in-law, John. We still have more than can grow out in the system but we're slowly moving them to John's. We figure we'll split them and then start harvesting when the system says so... as in when test levels go the wrong way.

We did end up with one bonus catfish. I'm guessing a channel since that is the other type of catfish sold by the place we got the tilapia. He's fun and now in the aquarium in the house until we are ready to use the aquarium for a brood tank.

As for heating, we've done several things.
1. We have a solar greenhouse that is 14 feet (4.26 meters) at the peak. There are crossbeams about 8-9 feet (2.5 meters) up. We put polycarbonate over the cross beams to minimize the area needing heat at night. Observations: At night the upper section is definitely colder (10 degrees F) than the bottom. During the day, it gets hotter if we have sun.
2. We covered the fish tank which seemed to gain us about 5 degrees (F) on average and has stabilized the temps in the tank a bit.
3. We also used 3/4 inch (18 mm) PE pipe to create a sort of solar heat collector. Water is pumped up by a separate pump through the pipe into the upper area (see #1) where the pipe is spread out to collect solar heat during the day. So far, we've noticed about a 3-4 degree (F) increase in temp when this runs. Note, we are in an area where we can go for days with no sun and then it might peak out through the clouds for an hour or two. This hour or two is when we see some heat gain.
4. We added a solar chimney that pulls air from the peak of the greenhouse with the outlet below the growbeds. We have buckets of water under the growbeds and the heat is blown amongst the buckets.

#3 & 4 are controlled by a thermostat that kicks on at 75 degrees F (24 C). We also have an electric oil-filled heater that is run off of another thermostat at night (forget the setting on that one, I believe it's 65 F). We do have heaters in the tank itself that are set for 65 F (18 C). The idea being it gives us 10 degrees wiggle room if we lose power during a storm. Tom is still looking for a propane heater for backup for that instance.

In case you haven't read the entire thread, our tank is buried in the ground with a layer of lava rock under the tank and insulation on the sides to insulate from the earth.

We should have our power bill in a week or so and we'll know then how "efficient" all of this is.

And for those who love pics

Hi Victoria
I like the way you`ve incorporated a huge array of simple yet effective energy saving features into your greenhouse. I`m sure they will pay for themselves in next to no time.
It doesn`t really matter how the efficiency turns out as any saving is a plus

Love the roof!

Great pics, Victoria! Positively inspirational. I have one of those oil-filled radiator heaters too, it's such an improvement over the ones with the exposed heating elements. Does the solar chimney drive itself or does it need some input? A fan?

HB

The solar chimney uses an axial fan that is placed in the pipe at the bottom. It draws the air down out of the high point. The fan is very energy efficient and uses very little electricity.

Wonderful thread-
I may have missed something, but here is a suggestion. When you are ready to harvest a tilapia or two, stop them from feeding for at least 48 hours. The flavor improvement is astonishing, and it reduces the fat content as well. They can go for up to a week with no feed prior to harvest.

We will definitely have to create a graceful way to purge them, badflash. We did eat the bigger ones we got at the Asian fish market. We pulled them from the tank and put them into a tank separate from the system. I was amazed at how much ammonia was in the tank in a short time. We did multiple water changes and then finally just pulled them. I felt like we were torturing the poor things. They were still delicious though.

I guess the question would be if having them in a separate tank where the regular system water is running will provide enough purging or if "fresh" water is really necessary. I'd hate to quit feeding the whole bunch just to eat a few.