Backyard Aquaponics
A place to discuss aquaponics

Well if you're not going to share your new story how about updating your old story PLJ.
Didja get some trout?

curiosity is killing me

Skeg, I rendezvoused with Troutman in the hills for a new batch of rainbow trout, as well as another consignment of silver perch fry.
Boss, please don't die on us!

As a consequence of my 'quiet time' away from the forum, I have so many stories to tell and information to share that I really don't know where to start. Perhaps if I list some topics then anyone who wants to hear what I have to say on a topic can let me know and I will start there. Since this stuff relates to my big concrete tank system I feel it appropriate that it remain here on this thread.

I have stuff to say about:

- Cohabitation of fish species in AP;
- Grow bed design issues, traps for young players;
- Silver perch positives;
- Very productive vegies, my first time growing these species:
- Trout growth rates differentiated by feed size, my views;
- 'Kamikaze' trout fingerlings; and
- Salvage of recently dead, but not killed, trout.

OK, I'll go first shall I ?

PLJ, tell me about: "Trout growth rates differentiated by feed size, my views" please!

Thanks for kicking things off, Guna.

The first two years that I reared trout (this is fourth) I had feed available for them that was an appropriate size, as they grew. At harvest time I had a moderate spread of sizes.
Last year I was caught (through poor planning) with bags of 7mm pellets and nothing else. I belatedly ordered some 2.5mm feed but, in the meantime, fed them 7mm. The fingerlings I sourced last year were a decent size for their age and seemed to have no difficulty knocking over the otherwise too large pellets, so I continued feeding the fish the 7mm pellets even after eventually picking up my order of more appropriate feed.

At harvest time (or mass die off time, as it turned out) I was surprised by the marked size differences across the batch. The spread of sizes was clearly more pronounced than in the two previous years and so, of course, I had to postulate a theory to explain the situation.

My theory is that when size appropriate feed is used then all fish, including the runts and the less aggressive, get to share in the bounty. Say for instance that the mass of the feed ration is 100g, then that may equate to 5,000 pellets which, if thrown in to the fish all at once, will mean there are many opportunities for every fish to rise and score a pellet or five or twenty. Even those that get less feed at least get some feed.

On the other hand, if the pellets are larger then the big hungry buggers and the bullies are advantaged because they will end up with more of the total feed, if for no other reason than that a % of the fish will simply not be able to swallow, what is to them, an oversize pellet. And fewer pellets means that a shy fish that can swallow the pellet will be more disadvantaged than it would be with lots more pellets to compete for. The gap then widens as the big grow bigger and the small or timid continue to struggle with crumbs, or with nothing.

Your thoughts?

Sounds about right to me.

How about bed design issues and traps?

I agree that sounds right, and it is the reason I was feeding a mix of 2mm and 4mm pellets to my 215 trout fingerlings from Arc en Ciel for a couple of months, until I was sure the smaller ones could handle the 4mm pellets. I think you also need to make sure there are enough pellets available such that there are still some pellets floating around when the more aggressive feeders are finished.

My bag of 4mm is getting a bit low and I've been mixing a few old left over from 2013 5mm pellets in for the past week, but there aren't many of them, so soon it will be a mix of 4 and 6mm pellets, and at the rate I'm getting through the food, over 1.5kg in the past 2 days, for (224 + 121) fish I'll need to buy a couple more 20kg bags of 6mm soon.

I am hoping for: "Salvage of recently dead, but not killed, trout."

How can a trout be recently dead but not killed? It sounds like a job for Inspector Clouseau!

Ok, Colum and Martin, I will address your chosen topics next, and at my first opportunity. Thanks for your interest.

Discussion of the chosen topics will need photographic support: I have the pics but will need to dig them out.

Good to have you back PLJ. I'd like to hear about very productive veges when you get a chance


Sent from my iPhone using Tapatalk

there're all topics I find fascinating, but I'll just do a ditto

Yeah, looking forward to it.

Nice profile pic too. Good to see you. I think I should probably find one I can upload too.

PLJ,

Welcome back, PLJ I'm interested in your information on the "Silver perch positives" when you have the time to reply please.

I think eating them would be high up on your list


Thanks for your reply in advance.

Yes, a mixture can work well. The greedy and aggressive fish are likely to target the larger pellets, we can probably assume, leaving more opportunities for the slow/timid/small fish.

I like your complementary strategy of introducing enough feed at a time that there is still food available after the initial mad rush. It won't be practical for some, though, such as me. My situation is that I don't have sufficient biofiltration, nor water exchange, to safely deal with more than Xg of feed at a time. (On the upside, my initial stocking rate is 1 fish/300L). I feed up to Xg of feed twice per day. The fish can readily consume more than Xg of feed at a time, so it is typically consumed within 15-20 secs, meaning the slow or dozy individuals may sometimes miss out. Note that if I threw in the same Xg of larger pellets, the feeding frenzy would be over in about 5 secs and even more fish would miss out.

Mine is a very competitive environment, possibly explaining why I have yet to produce a trout heavier than 600g.