Culling Fish. The Dreaded Part of Breeding

[AllFishNoBrakes]

Hey everyone. 
 

I know not everyone likes to think about this aspect, and most don’t want to talk about it, but I’m curious; when you need to cull, how do you do it?

I’ve had to euthanize a couple fish throughout my couple of years hobby, unfortunately. I’ve had some fish with tumors, some that appeared to not be having a great quality of life, etc. The best way I’ve found/used is with clove oil. 
 

I’m currently in a bit of a quandary in that I have a couple Angels I’ve raised and want to trade soon, but I’ve noticed a couple are missing gill plates on one side, and another has a bent ventral fin. While the fish are absolutely healthy and otherwise are doing incredible, I really don’t want to taint my reputation with my LFS’s by knowingly trading fish that I feel are subpar. 
 

I also have a couple of Glowlight Tetra’s that swim almost vertically. I’m chalking this up to old age as I’ve had them for 2.5-3 years, and they still look healthy. I believe these fish are still living a great life, so I have no need to euthanize them at this point, but should the day come that they cross the line to not living a good life I want to be prepared. 
 

This post is mainly about the Angels as the whole reason I raised them was to trade them. As much as I’d love to keep a separate tank of misfits I couldn’t sell it’s just not possible due to space. My 2 bedroom apartment is MAXED out with tanks at this point, lol. 
 

When you have to cull fish, what’s the most humane way you’ve found to do so?

Thanks in advance for sharing your thoughts, opinions, and experiences on such a sensitive topic. 

[modified lung]

Clove oil or tricaine mesylate + baking soda are generally considered the most humane ways to euthanize fish.

[AllFishNoBrakes]

On 9/27/2022 at 9:02 PM, modified lung said:

Clove oil or tricaine mesylate + baking soda are generally considered the most humane ways to euthanize fish.

Clove seemed like the most humane, and most approachable option when I researched this early on. I’ve never heard of the other option; I’ll have to look into it.  
 

For this specific purpose I almost wish I kept an Oscar or a Bass or something, but honestly I’ve made it this far without having to make this choice until this point. 
 

FWIW for anyone that thinks euthanizing is a terrible thing; I also listed the fish in question for free on Craigslist, with the caveats that the interested party must prove to me proof of testing that they have a cycled tank via photos of test results, and must prove they have a tank size large enough via photo proof as well. 
 

 

[modified lung]

You don't have to defend yourself for culling. In the wild it's common for a certain percent of fish to hatch with developmental disorders. They usually get taken out by predators really quick. You gave those fish a much longer and better life than they would have had otherwise. 

[AllFishNoBrakes]

@modified lung Appreciate the kind words. For whatever reason, it’s way easier for me to feed fry to other adult fish, or the thought/action of feeding fish to another fish feels way better than simply euthanizing fish. After all, it’s common knowledge that “fish eat fish” and “if it fits in another fish’s mouth it’ll eventually go there”. I simply don’t have that option available to me even though it’s preferred. 
 

If another hobbyist doesn’t want the less-than-perfect fish I have, I know what I need to do. I’ve researched culling before, but it seems like nobody wants to actually talk about it. I get it, it’s not the fun part of the hobby, but I am curious what others do to keep their stock/offerings of the best quality. 
 

If nothing else, I hope that others can learn from this thread and some resources of what people actually do and why are available to other hobbyists. 

[TheSwissAquarist]

I agree, Clove oil is best.

[gardenman]

The survival rate in the wild is likely less than one percent and even the most ruthless culler saves more than one percent of their fry. I can't find any stats estimating the real-world survival of fish fry in the wild, but given the number of eggs laid and the relatively small number of adult fish, I would assume less than 1% would be about right. Pretty much everything eats fish, fish eggs, and fry, so yeah. Going from a fertilized egg to an adult fish is very challenging. Captive bred fish have a much better survival rate and can survive with defects that would doom them at a very young age in the wild.

[tolstoy21]

Yeah, if you're going to breed fish, you're going to have to cull.

I don't want to wander down the path of ethical/philosophical thoughts on this fact, other than to say it's a necessity. If you feel bad about doing it, that's a good thing and a sign that you're a thinking, feeling being. However, that doesn't alleviate the deed that needs to be done, nor make it any easier.

I agree that you certainly do not want to sell fish that have defects, unless the person buying them, or that you're gifting them to, understands what they are getting. But in reality, you'll likely end up with more fish in this category than you can find homes for, or reasonably house on your own.

For me, if I have fish that don't meet the standards of what I want to sell, but are otherwise perfectly healthy fish with no genetic abnormalities -- like if the fin color or shape or body color is subpar-- I just sell them at a reduced rate and clearly state why they are reduced, but also that they are still great fish. I'd rather make little profit, or cut even, on these fish than cull them, if I don't have to. 

Now there are obvious culls, like fish that have horribly bent spines, or under developed swim bladders. These are obvious cases where euthanasia seems more appropriate (and a tad less guilt inducing; at least, this is what I tell myself). But then there is that grey area, like the Angel fish that you describe. Or when you simply have fish that you can't sell and can't reasonably keep. And this is where hard choices come into play. 

I'm sure none of this reply makes things easier other than to say that this is a reality that goes hand-in-hand with breeding. When I was younger I knew someone who bred show rabbits, and he would give me his culls to feed to my pet python. So, this isn't just a fish breeding thing.

What methods do I use personally? Oscars (but only occasionally). More routinely, I give my sacrificial offerings to the porcelain god. 

[PerceptivePesce]

I plan on burying deceased fish in the compost. They make excellent fertilizer, and will live on in my plants 💙

What does clove do? Make them sleepy?

[Patrick_G]

On 9/29/2022 at 5:48 PM, PerceptivePesce said:

I plan on burying deceased fish in the compost. They make excellent fertilizer, and will live on in my plants 💙

What does clove do? Make them sleepy?

You first add the fish to a very dilute solution of clove oil, that sedates them, then you add enough to euthanize them. 
 

 

 

[WhitecloudDynasty]

When and how to cull is 100% up to you. Every breeder have their own goal/breeding program.

I cull all of my fish at 6month other than my rosy barb. I keep very small number of breeder or back up breeder due to space. So everything else is call culls.

There are good culls..fish that are healthy, great conformation, ect... but don't meet my breeding programs or goals. These can be sold or given away.

There are bad culls...fish that are unhealthy, bad conformation, ect..unhealthy fish need to be put down, bad conformation fish can be your feeder fish. None of these should leave your system. I don't trust ppls won't breed from them.

[Fish Folk]

Good thread. Thanks to all who have shared.

Take care not to violate your conscience, wherever that’s at for you. It is good to honor your inner seat of ethics.

For me, there was a season very early on when I refused to cull, considering it a brutal cruelty. Eventually over time — as others have said — I came to realize that culling was necessary. But now, I am more keenly aware of the cruelty of _knowingly_ letting genetic defects propagate. At this point, my conscience bothers me if I don’t cull!

I am blessed with an exceptionally good relationship with my LFS. I take my culls there and watch as their Arowana, Oscar, or similar reconstitutes some protein.

[Guppysnail]

I have been through the same learning process as @Fish Folk.  I have homed genetic defect fish with me. Nothing sub-par ever leaves my care for fear those genetics may accidentally be passed along by an unsuspecting hobbyist. If it is seen early I now cull immediately.  If it does not present until older AND I have available tank space it’s a choice I make each time.  Will this fish have a good quality of life in my care for its lifetime.  Do I have tank space I am willing to dedicate for its entire life expectancy as I can never house opposite sex same species fish with them. I currently have one stunted growth male guppy who got caught in the planter so did not eat well at critical stages. I keep him in the bachelor tank on the off chance it was a genetic issue. 
In the wild nature culls.  I feel it is my responsibility to assume the culling duty in my tanks that occurs in the wild. 
It’s not right for everyone so I do not preach culling. However I urge not selling/trading or giving to LFS genetic issues without full disclosure and a caution to not breed. 

Edited September 30, 2022 by Guppysnail

[gardenman]

Keeping a few large predators does help solve the issue of culling. No matter what you feed your predators, it was in all likelihood at one time a living fish that was killed to make fish food. (Or human food.) The fish meal that often makes up a large part of the pellets and flakes we feed our fish were living fish that were killed to make them into food. When we feed them pellets instead of live fish, we're just avoiding the killing part ourselves. Fish still die to feed your other fish. It truly is a fish eat fish world out there. Well, it's an everything eats fish world to be exact. Most of my cat food (canned or dry) has some fish component to it. They didn't just wait for a dead fish to wash ashore and then rushed it to the processing plant. They went out and caught living fish and then processed them.

In my younger days, when things were a bit less regulated, most local pet shops had a caiman or two. Why? To dispose of unwanted fish, dead or alive. They were sort of a living garbage disposal for pet shops. Have a dead hamster, fish, smaller bird, etc., drop it in the caiman tank and it disappears. No muss, no fuss. 

Whether you feed your culls to other fish or buy pellets, you're still feeding them fish. You're just a step or two removed from when the fish you're feeding them were living. And if your culls have been raised right, are healthy, and well cared for, it's hard to find a better food for a predator. And the fish you're feeding to predators as culls likely ate their younger siblings at some point or would have given the chance. It is a fish eat fish world out there.

[Minanora]

I use clove oil and then compost them. I compost excess pest snails as well. I have a special blender pitcher specifically for the compost, so I don't ruin my good pitcher with scratches from egg shells, snails etc. Yes it's gross but I have amazing compost. 😆

[sumplkrum]

I cull my guppies. If you let too many fill up the tanks, they become stunted.
It's important for the ones you want to keep to have grow-out space.

I do freezer to compost.

[AllFishNoBrakes]

Looks like someone who actually knows what they’re doing is interested in these couple Angel misfits of mine. They have been spared thanks to a kind soul that has way too many tanks (like the rest of us), and actually knows what a cycled and seasoned tank is/means. 
 

For the record, I’ve definitely culled fish before. While it’s not my favorite part of the hobby, I was more curious what others do. I appreciate everyone chiming in with their preferred methods!

[KittenFishMom]

The LFS has not been doing well since a chain pet store opened across the street. I think I will find out tomorrow if my guppies are heading toward clove oil.

Any advice for using clove oil on a large number of fish? It will have to be all the females and most of the males. I would guess well over 100 fish. I only want to keep one 10 gallon tank of males, and 15 I am shipping out.

[AllFishNoBrakes]

I’ve only ever done a single fish at a time in a small cup. I would assume for larger amounts of fish and water volume it would just be a larger amount of clove oil 

[MannyThakk]

On 9/27/2022 at 9:44 PM, AllFishNoBrakes said:

Hey everyone. 
 

I know not everyone likes to think about this aspect, and most don’t want to talk about it, but I’m curious; when you need to cull, how do you do it?

I’ve had to euthanize a couple fish throughout my couple of years hobby, unfortunately. I’ve had some fish with tumors, some that appeared to not be having a great quality of life, etc. The best way I’ve found/used is with clove oil. 
 

I’m currently in a bit of a quandary in that I have a couple Angels I’ve raised and want to trade soon, but I’ve noticed a couple are missing gill plates on one side, and another has a bent ventral fin. While the fish are absolutely healthy and otherwise are doing incredible, I really don’t want to taint my reputation with my LFS’s by knowingly trading fish that I feel are subpar. 
 

I also have a couple of Glowlight Tetra’s that swim almost vertically. I’m chalking this up to old age as I’ve had them for 2.5-3 years, and they still look healthy. I believe these fish are still living a great life, so I have no need to euthanize them at this point, but should the day come that they cross the line to not living a good life I want to be prepared. 
 

This post is mainly about the Angels as the whole reason I raised them was to trade them. As much as I’d love to keep a separate tank of misfits I couldn’t sell it’s just not possible due to space. My 2 bedroom apartment is MAXED out with tanks at this point, lol. 
 

When you have to cull fish, what’s the most humane way you’ve found to do so?

Thanks in advance for sharing your thoughts, opinions, and experiences on such a sensitive topic. 

Ive seen peope like someone has mentioned before to give them for free on craigslist, facebook, offerup. Etc. Maybe even consider someone that has turtles or bigger fish they can use as feeders? Ive heard @Cory mention that on his livestreams. I pick up baby guppies for my senegal bichir to feed on. Had a few grow to adults and simply just make more fry!

[TheSwissAquarist]

On 10/19/2022 at 10:30 AM, MannyThakk said:

Ive seen peope like someone has mentioned before to give them for free on craigslist, facebook, offerup. Etc. Maybe even consider someone that has turtles or bigger fish they can use as feeders? Ive heard @Cory mention that on his livestreams. I pick up baby guppies for my senegal bichir to feed on. Had a few grow to adults and simply just make more fry!

Lucky Guppy😉

[AllFishNoBrakes]

Luckily, these guys went to a new home to a lovely hobbyist I met on Craigslist, free of charge of course. I’ve tried to give other fish away and only asked for proof of testing to ensure their tank was cycled and it was a nightmare. This time, the lady was happy to provide test results, show off some of their other tanks, and I was assured they were only going to be displayed and not bred as they had some aesthetic issues. Overall, I’m happy with the outcome and was surprised Craigslist actually worked for once. Guess it was meant to be. 

Edited October 19, 2022 by AllFishNoBrakes

[bhaminal]

Rubbing alcohol is very quick and effective. Also cheap and widely available. Alcohol evaporates off and is non toxic if you still choose to compost, which seems like a good option.