Pond Boss Forums MANAGING AN EXISTING POND Corrective stocking Blocking net for cnbg spawn and grow out

I looked into the Forum list for using a blocking net to isolate an area where I might add a few 7" cnbg. And hope for a spawn and then grow them out to 3 or 4". I did not find much information so I thought I might ask if anyone has had any success in getting a cnbg spawn behind a net and then growing them to a good forage size? The area would be in a corner of the pond where the shoreline makes a 90 degree turn. Run a net across that 90 degree turn. Maybe a 40' or a 60 foot sein as the blocking net. Or use some plastic deer fencing I have and may be add to the net making it more ridged and maybe it might raise the blocking net above the water line. This should give me some 4' water depths. If it were to work for a spawn, how many could be grown out from say 10 cnbg in a small area. Plans are to feed them along with maybe adding some fhm's and maybe a wood pallet for the fhm's to spawn on and help feed the cnbg. I did find where Eric, Al and Shorty have used blocking nets. Lessons learned you guys might share?

Tracy, I've screwed up blocking nets in several different ways. I'll post a few later today.

If you set cages around a dock YOY BG will swim into the 1/2" cage material opening and stick around indefinitely as it allows escape from predation. In a couple months these fish are too large to swim out of the cage and provided you feed them you can easily grow out to 3-4". A lot easier than a blocking net just an idea that may work for you. I end up with a lot of coincidental BG annually this way.

BG spawning behind a "normal" blocking net (1/4"-3/4") will result in most if not all the fry (0.2"-0.35") swimming out of the netted confinement area. Fish are explorers, food seekers and always looking for 'greener pastures'. Also small bass fry 0.7"-1.2" will move through the net into the conainment area. When the mesh size of the blocking net becomes small (1/16" or less) it quickly clogs heavily with coated algae and periphyton which prohibits water exchange and drags down the net so larger fish can avoid the net block.

I concur with TJ. A more productive plan is to use a fish cage you buy or build for some small BG that you purchase. Feed them high qualtiy food for a few months and then release them. The method will provide BG of 3"-4" quicker that using a blocking net starting with fry.

Bill, you and Tj may be right, I suspect you are after seeing Al's short comment about screw up's with blocking nets. Highflyer an I had a good conversation over the phone. we talked about blocking nets.

I might be wrong but I remember seeing where maybe Shorty had some luck with smb and Eric seemed to have some luck with it from his comments here.

Ok Bill and Tj, I have seen where cage raised fish may be a fairly new way of fish farming and growing out some bg to 3 or 4" bg could fall in that category. You have any idea how many you could raise in a 4x4x10' cage? And Tj going your way might save the money from buying small bg but not sure how many I might persuade into coming to a cage and taking up residence. One reason for the blocking net idea was to not spend any or little money on this venture. Catching a few nice bg, putting them behind a net, feeding once per day along with Fhm's for forage now seems to easy and not work out as planed. And I was hoping for 500+ 3 to 4" bg before it was all over. Looks like it may have to have more thought into all this

Tracy, edges should probably be your biggest concern with blocking nets. The bottom, banks, and surface can all be escape routes if proper setup care isn't taken before you add any fish. I've yet to set up a blocking net that didn't eventually open up from limbs on the bottom of the pond, quick water level rises that lifted the net off the bottom, or windy day tree trash that fell on the top line, and dropped the net below water level. The majority of fish did stay in the blocked area, but there were always interlopers of some kind that showed up for a meal, and targeted fish getting out.

TJ and Bill obviously gave you great info. The cages and blocking net nets will algae up, and I've had good luck with a few single sexed tilapia thrown into the mix.

I'll try blocking nets again, and it's a fun project, but IMO neither a blocking net or cage will produce the pure numbers a dedicated water filled hole in the ground will. Ultimately, I would think you're wanting thousands, to tens of thousands of 3-4" CNBG, and I think that's best accomplished when done in a single species dedicated pond. In essence, this is a hatchery project, so that's probably the fastest and in long term effort the cheapest, so that's how I would go.

here is a pic of my shark cage. i toss a little food in every time i walk to the dock. all of these fish went thru the 3/4" mesh when they were small and eventually trapped themselves as tj was mentioning.

Al, you put a smile on me this Christmas morning because I know you are correct in having a single species dedicated pond. Thousands of bg sounds good But until I get that done I thought I might see what I could do with what I have for right now. I like the cage idea and with your comment here then maybe I might get a blocking net a good shot. We will have some nice weather in 45 days or so and I am looking for a place that is not all sand for a forage pond. The ideal place had 100% sand, and I have little idea why? It is right next to the big pond. Just blew me away as to why a few feet made such a difference in the soils. I have another spot picked out but I need to look at it closer and give it more thought. The downside is it would have to be seined for harvest. The blocking net, just drop the net I must be getting lazy in my older years.

Thanks Scott for the picture, good information. What was the time frame for this to take place?

Tracy, gotcha. Others can tell you what would be the best parameters are for a blocking net, but personally, I would double up on bottom weights and surface floats, get the netting treated, and add an extra 20% on whatever length and height you need.

i would guess 2-3 months, but i don't really remember. looks like some of these were close to the 5 inch mark by counting the 3/4" squares. i live on my pond and most days i would toss them food 2 or 3 times a day. i made the square feeder ring that floats, i think that helps get them in there initially by holding the food. i feed them am 600 so the little ones peck at it for a while.

Scott that's exactly what I'm talking about...granted, we can't control the numbers as they are incidental swim through larval fish, but it's a free collection/grow out effort. Thank you for sharing that timely post and photo.

Tracy let's get to the root of your issues - we are here to help. Are you seeing low WR LMB? Gaps in your BG population size distribution? Let's identify your impetus for the BG stocking project. If we back up to the beginning we can all pitch in with some ideas. Could it be as simple as culling some LMB and placing dense cover shallow for BG predation escape? That's a lot easier to navigate than installing blocking nets or digging forage ponds.

On forage ponds....I have 3 and they sure feel as though they've paid for themselves by now from a labor/effort perspective...trick is to create/excavate them for easy collection. I'm a fan of 6" ball valve installed in deepest part of the pond - I don't use gate valves any longer. Pull the lever, drain pond into horse tank with a cover - water/fish in, water out, fish in - it's a one man effort. I'm with you on seining - those days are hopefully numbered for me. No fun...and all my buddies have gotten wise to my invitations to come out and fish after they help with a "couple little things". Doesn't matter how much booze I provide or how much stuff I blow up.

i like putting the valve on the dry side of the dam and have the pipe stubbed out to the deepest part with a stainless inlet screen. usually make the screen out of 1/2" stainless expanded metal. i have done that on both ponds (i don't have a forage pond) and run it in the same trench as the main stand pipe.
Sure makes it easy to drop the pond a foot or 2 for maintenance/weed control.

My goal is to get as many 3 to 4" cnbg as I can get. Why? To grow lmb to 6 to 10 lbs and larger as fast as I can. For now, my lmb that are at 17 1/2" or larger seem to be running 10 ounces over the standard charts. And I would guess from catching a few in the 15" range the lmb look to be fat and sassy but it's been awhile since I weighed any of the lmb in that size range. I am positive they would also be above the line on the chart. So, here is the deal. Year before last I was short of 2 t 3" cnbg in March. We then added 9 brush piles along the shoreline and we added 25lbs of FHM's to take the pressure off the cnbg. 60 days later, I had small cnbg everywhere, I had never seen so many before. Those big white Crain's stood side by side on one shoreline along with several GBH. Even with the GBH being territorial, they didn't even run the other off. Now, that is a lot of 3" cnbg. This might be crazy, but I would like to see that many small cnbg again. I am going to try that same path again but thought a blocking net/capture box trap might assist in me getting there.

I also have problems getting much assistance at the pond

"I also have problems getting much assistance at the pond smile"

This seems to be an issue everywhere, including here!

Dense, shallow cover is a great start and you've already seen some results. If you have a dock you can pull umbrella nets around the edges and collect thousands of BG fry weekly with minimal effort. Cage them with small mesh [1/8"] and feed them daily. Add a few crayfish to each cage to help with the filamentous algae growth, they'll climb up and down the cage and keep it clean in my experience and you'll only lose occasional BG to them. Cages cost less than $50 and 1-2 hours of labor and you could easily raise 500 BG or more per 3x4' cage and release at year end. You have a free source of YOY BG and with periodic feeding can grow to 3-4" easily by end of season for release.

Tj, Pardon my stupidity, what is an umbrella net? Casting net I'm guessing? Ok, now with the pier. I have a floating 12x16 pier that sets in 2 to 4' of water (easy to move with attached trolling motor) not that far from spawning area. Take my 40' sein and drag it under my pier to remove any predators and then use plastic 3/4" fencing placed around the pier top to bottom. Making this my cage and start feeding inside the netting. Or like you say catch some smaller bg, place them inside the net and grow them out. I wonder how many I might grow out there? I may not need to do this but it might insure I get some bg to 4". And I'm planning on the blocking net also in that one corner of the pond. This might all fail but it gives me something to do at the pond that might help to keep the larger lmb above the line on the WR charts. Now I have to come up with a way to keep the plastic fencing tight to the ponds bottom and slightly above the waters surface.


Thanks TJ

I have been researching fish caging on the TMAU agg website and came to the conclusion I will need to use 1/2" plastic fencing. Good thing to because I was planning on using 1/4". Now I am not sure what size to use as suggested by Tj. This looks promising for raising some cnbg to 3 or 4". Looks like I might be able to raise a thousand using cages. Thanks for the help guys.

Sorry Tracy been away a while - umbrella or drop nets are simply 36 or 42" square nets supported by a frame one drops down, waits a while, then pulls up. Think a very small vertical seine net. They are cheap and very effective around a dock to sample YOY fish - sometimes I'll pull through a school and have 100+ YOY BG in one net pull. You can get 1/4" up to 1" mesh 3' wide fencing at any box store pretty cheap in rolls 25-50'. 3' depth cage for BG is plenty...for YP I like my cages deeper - like 5-6', so those are built a little differently. My original intent was just to share what I do around my dock to collect and grow out BG - it's little effort and little to no cost except for feeding. Sounds easier than the blocking net project?

Thanks Tj, I have several rolls of plastic deer fencing, in fact, I pulled it out yesterday for a look see. Looks to be 1". If I double rolled it around the cage it could make the openings a little smaller. Thinking a round cage using pvc might be the easiest cage to build. I am not sure I need to build the cages for growing out some cnbg to 3 and 4" but I figure why not give it a try. The lmb should like it.


I've pick up a dozen Christmas trees so far for shore line cover. This has worked in the past where it seemed to improve bg fry survival. I have very little vegetation in the pond so the Christmas trees bunched in a few piles seemed to help fry survival. I will add some cedars to the mix also. I still plan on using a blocking net in one corner of the pond. Looking at doing it with the deer fencing and some T Post. I may have to add some 1/4" netting to the fence. Also thinking of adding a Christmas tree or two in the blocked off area for cover.

So I did this. Not that I doubted TJ's experience and advice, but I was surprised at how quickly small fish started coming in the cage. I'm tossing a few 1/8" pellets out every morning and evening, and the fish are staying in the cage. TJ's explanation and Scott69's pic convinced me to try it.

It will not provide enough forage to have a positive effect on my predators, but it is a great option when I hand feed my LMB, as keeping a cache of smaller CNBG handy was always a problem. Very handy cage to have.

Sweet Al - it’s nice to have a stash of feeders for your lmb babies. Hand feeding predators is a hoot!

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