Fish on Trial.

What will be the verdict?

We have started a feed trial with Jade Perch. The idea behind the 12-month trial is to see just how well the Jade Parch will grow being fed anything they will eat that can come off the land rather than use fish feed pellets that contain ocean derived fish meal.
With a view toward long-term sustainability, I feel we need to discover and refine feeding methods that are not dependent on ocean fish stocks. Seems elementary, but I really want to see just how well it will or will not work.

Aquaponics policemen.

Aquaponics policemen.

Expectations: I believe we will get the fish through to the 12-month point in a healthy state, after all, Jade Perch in the wild eat plant material and algae etc. I imagine that we will see slower growth in the plant fed fish but I believe they will be very healthy.

Time will tell.

In my INDY 23 system I have 2 x IBC tanks that are all part of the same system. Same water same pump system etc. I feel it is an ideal setup to test two identical batches of fish that share the same conditions except fo the feed they get.
There are 65 Jades in each tank. The fish are supplied by Ausyfish at Childers.
They have been in the tanks for one month. The trial feeding started 1st March.
Weigh in on 1st April.

Method:
The batch of 130 fish were evenly divided as to size as near as we could. Very difficult when they are so small approx 10g each fish; so we started with 650g of fish density in each tank.

Tank "A" is been getting up to 50g of 2mm pellets per day.
The pellets are as below
Crude Analysis
Protein Min 35 %
Fat Max 10 %
Moisture Max 10%
Ash Max 11%
Ingredients =
Chilean Fishmeal, Wheatflour, Soybean Meal, Shrimp meal, Squid, Aquamix,

Tank "B" is getting a diet of lettuce, cooked carrot, cooked pumpkin, Kang kong leaves, honeydew melon, eggplant, cucumber. It is difficult to know just how much to give tank "B" every day but we are getting better at keeping the feed up to them.

This is a piece of eggplant that they demolished overnight.

This is a piece of eggplant that they demolished overnight.

First weigh in on 1st April.
Sample of 20 randomly caught fish from each tank gave the following results.
The fish were weighed as a batch.

Group "A" = 30g
Group "B" = 23g

Group "B" have not put on much weight at all; 3g over 20 fish. So we need to up their feed somewhat.

 

This is the lettuce when they have stripped it of the green leaves.

This is the lettuce when they have stripped it of the green leaves.

Fish Food – How Much Do I Give Them Per Feed.

Fish Food—Feeding your fish using commercially available sinking or floating pellets.

The fish food we supply is suitable for all Australian Natives.
The fish food has NO land animal content.  This is a very important consideration. Land animal content is usually made from lot fed beef ot swine leftovers that are laced with antibiotics and the like.  These unwanted drugs will end up in you and your family when you eat the fish you have raised.

Be careful not to over feed your fish. This results in wasted food and fish food lying around on the bottom of the tank can cause an increase in the ammonia levels in the tank.
There are formulas that can be used to calculate exactly how much food to give your fish per day.  The formulas are grams of food per grams of fish weight.  To exercise the formula correctly requires that a number of fish be caught and weighed on a regular basis, establish an average fish weight, then  calculate the correct amount to feed.

For domestic home based systems this is impractical, so a “by observation” method is better employed.
Observe carefully as the fish take feed. Any food not taken up within 20 minutes or so is too much. Regulate the amount of food given to the fish at each feed time by observation. If your new fish are very small, use a coffee grinder or similar to break down some of these pellets into finer particles for the new small fish to consume.
Gradually increase the size over the first weeks until they are feeding on the full size pellet. New fish will not usually feed much in the first few days., so be patient with them giving them small feeds until you see evidence that they are feeding. If you disturb the fish this may put the fish off their food. Changes in temperature and other conditions may also put the fish off feeding.

It is a common problem, overfeeding the fish…so exercise caution.
Australian natives, almost withour exception can go for extended periods of time without being fed.   If you need to go away for a week, it is better to purchase an auto fish feeder device (available from most aquarium shops) to give a regulated amount of feed per day.   If you cannot do that, it is better not to feed them rather than get a neighbour to take care of the task.   Most inexperienced but well meaning folk will overfeed your fish, resulting in an excesses of rotting fish food in the tank which will cause an ammonia spike and the possibility of fish deaths.

I hope this is helpful.

Murray