Backyard Aquaponics
A place to discuss aquaponics

The duckweed looks generally healthy now.

I certainly cant grow it in my fish tank because the fish eat it too fast, although I've never tried covering the tank. The problem with duckweed in the tank is that the more they eat, the more ammonia the produce, and the less duckweed there is to deal with it. If your water warms up a bit, and the fish get more active, they can upset the balance very quickly. Basically there is no way to control their food intake.

It's probably not an issue for your system with the number of fish you have.

Did you try tuning on your filter to lower the ammonia and nitrite levels? It seems the filter just has a high surface are inside to maintain a bacteria colony, so it might be a good idea to keep running it for a while once a day to keep your bacteria alive.

If the fish are not eating, they will die!

The photo of your silvers show that they have very large heads, for body size. A sign that they may not be eating. Fish will use their own body mass, as caloric intake, when they are not feeding.

Were the silvers eating man made food or were they being feed live food prior to being sold? Also, if the goldfish are dominating the food that is being delivered, how are the silvers going to be able to feed?

Have you tried segregating the fish? Place a plastic net type barrier (similar to gutter guard) in your pond. Once they are seperated, see if they are feeding. If they do not feed, you could try some live feed such as brine shrimp.

The fish grew considerable in the first few weeks in the system.

Silver perch have been in the same pond for about 5 weeks. They grew more than 100% during this period.
It is true that larger gold fish dominate food and silver perch do not come near goldfish, but the pond is 5 metre long and I distribute food, so perch have own space. There are a lot of algae on pond wall.

About the head size in relation to body, it could be a bit of photo distortion, but it is an interesting point I would like to think about.

Not a food problem by the sounds of it

Have you given any thought to what level your fish are eating at. Goldfish tend to be top feeders, they collect their food from up near the surface of the water. I think you may find that the silvers are middle feeders and catfish tend to be bottom feeders. Perhaps 2 different types of feed might help.

Fish can live for some time without food. The damage comes from the uneaten food rotting and changing elements like the ph or even your ammonia levels. Goldfish tend to be able to handle higher ph levels than silvers.

In our experience algae should not be an issue as long as you have plenty of oxygen going into the water (good air pump).

must say you have a very tidy system, enjoy.

you can hydrate your floating pellets overnight to get them to sink

Are you running your filter?

If not, you probably should.

When ever anything goes wrong, throw as much pumping, air, and filtration as you can.

Your filter already has a bacteria colony, and running it will help seed the gravel beds.

This is probably worth adding to your notebook.

from this post on ammonia

from this very useful section

Thanks for your compliment, but the system is far from settled as you can see.

Regarding feeding behavious, yes, I did notice that silver perch never come up to the surface level. But not having any experience of raising silver perch, I thought this could be because they were still small and cautious of human being. Anyway, I notice the difference compared to goldfish.

However, both goldfish and silver perch have changed their behavious over time, in general becoming less cautious and coming closer to the feeder.

Will write about food when I will be making my second week report tomorrow.

Sejin

Yes, I have done that especially when pellet is large.
Make it soft rather than breaking them.

Sejin

My silver perch always stick to the bottom unless they are sick.

Sometimes they will take pellets off the surface, and will come to the surface for lettuce and senposai, but generally prefer the bottom.

Here is a report on the vegie growth at the end of two weeks of my first AP set up.
My assessment: adequate but not spectacular. May have grown better on soil. At least, it is not especially better.
This much growth could be achieved even without fish, I think.
What more has to be done?

See how things are looking in another two weeks...

I should have made clear that in the previous the plants started from seedlings.
What happend to those that started from seeds?
At the end of the first week, only lettuce sprouted.
In another week, other things began to emerge. Being somewhat of a pessimist, I was preparing myself for the worst, no other emerging and lettuce not growing and all of them dieing small.However other plants came up though lettuce growth still seems a bit retarded.
These may be cucumber and egg plants.
I think I can now allow me to raise expectation a little bit higher: that all plants that started from seeds grow healthy even though their growth may not be spectacular.

The one in a meshed pot is tomato seedling that I put in this growbed for seeds for comparison.

Sejin