Backyard Aquaponics
A place to discuss aquaponics

Good point arbe, brown trout grow much slower than rainbows.

Two reasons for this - one is that they are a very different fish with different needs and all different types of fish have different growth rate. I guess we all know that already... Rainbows have a very high conversion rate hence the reason that they are raised for table food - much cheaper!

This has led the industry to do far more research in rainbows and the food they need. So what about browns? In captivity, they are generally feed the food that has been manufactured for rainbows. This food does not contain the appropriate caloric and nutritional needs that browns need - hence a slower growing fish which.... is not fed an appropriate diet - will grow even slower.

Please note that I am no expert in this at all. This is just some of the stuff I have learnt, over the last three years, raising trout at home.

As I have feed my browns a lot of live food and high protein food such as fish offal, I have had them grow much faster than hatchery raised rainbows. Hatchery fish are not well looked after and are kept in very dense population.

Having said this, my rainbows grow much faster than my browns, by a long way. That's because of the food intake to growth conversion rate.

Its all quite fascinating. I plan to place another IBC FT next to the current one, to hatch/raise trout in this winter, instead of using the aquarium.

I have goldfish in my AP

Thanks for the extra information everyone. No offence taken Arbe... just was trying to work out what you meant.

When we first got into trout a few years back we were given a mixed batch of albino rainbows (not sure of ploidy), normal triploid rainbows, and a few browns. The browns were much slower at everything and less aggressive so they did poorly with the rainbows because they couldn't compete and for some reason were hard to get them eating the pellet food (maybe what you said, DunderOz, about it being unsuitable is why). The browns were given to us by mistake as they just scooped out 30 fish from their ponds and gave them to us. The albinos didn't do as well as the wild-type rainbows and I put that down to their vision not being as good. They still grew really quickly and are quite a beautiful fish. The triploid rainbows grew really fast.

I applied to fisheries to get two pairs of diploid rainbows to see if we could breed them at school (and was turned down... they offered us eyed tiger trout eggs instead... they really don't want to relinquish control of the breeding even if it's for a school). I thought it would be an excellent learning experience for us to go through the process of getting stock fish and my mate who supplies rainbows to farm dams said that they come into breeding condition in the winter in tanks (all other conditions being to their liking) whether they can actually breed or not. What Troutman mentioned about rainbows not being able reabsorb their eggs is a bit of a worry. Nobody mentioned that to us before and I had intended to grow them for a few years before trying to breed them. He (Dan, my mate), was saying that when they are ready the eggs and milt virtually burst out of them with only a little encouragement.

When visiting the aquaculture setup at the AMC they showed us the rainbow trout breeding facility. It was basically a cool room. They said that they kept them cool (about 7-10 degrees C), and that at those temperatures the eggs took about 2-3 months to hatch. The room had a long (10ft ish) shallow (~10cm) stainless steel trough with a perforated false floor to keep them off the bottom and to allow water to slowly flow over and under them as it would in an irregular gravel bed. Not sure if they had a fungicide in there. In the past I would add methylene blue to (cichlid) hatching tanks to prevent fungus and also to increase the oxygen uptake of the eggs. They also told us to be very quiet and not bump the trough as the eggs didn't like to be disturbed (which doesn't make sense to me given the turbulent nature of the water they are often laid in... but we were careful all-the-same). Water was circulated from a low sump at one end to higher one at the other end. They just stripped the eggs into a bucket then stripped the males into the same bucket and stirred it together, rinsed them and placed them in the trough (not sure how long they left them together in the bucket). The sump at the exit-end doubled as a biological filter.

When I mentioned a simulated gravel-run I meant I have a trough about 4ft long that sits on top of my main FT that receives water returned from the growbeds. It can be set to two levels. One is about 10cm deep and the other about 30cm deep. What I was planning on doing was setting it to the low level with some gravel in the base to allow the water to flow around the eggs more freely during the winter when water temps are sitting around 5-10 degrees C. The trough has two hardwood covers sitting over it to keep them dark.

Dunderoz, thanks for those links! I will read through them tonight. I agree! It's really fascinating and I'm tempted to just go and catch some brown brood stock to keep here at home, when everything is up and running, to try it myself. The tiger trout eggs sound interesting too... I just don't want to have to buy new stock each time I need them when I know how to breed them myself... I've been breeding fish since I was 10 years old (which is why I'm now looking at the blackfish as they are not so tightly policed).

Thanks again for the tips and links