Magic Number

[KentFishFanUK]

Just something I was pondering and wondered what you experts thought -

Every time we talk schooling/shoaling or even just most small fish we obviously say they prefer to be in groups right. I get that that's because of how they live in the wild, safety in numbers etc. 

When stocking our aquariums the majority of species that like to be in groups (or at least the common ones I own or have looked into - be it Corydoras, neon tetras, multi's, some even say it about pea puffers and endlers and I'm sure many many more) the most common general consensus seems to be that the bare minimum number is 6. 

What makes 6 the magic number?

I understand more is always better and that in the wild they would live in huge colonies but why 6 as the bare minimum? Why not 5? Or 10? Or 20? Or 2?

Is there a scientific reason? Was there a well thought of scientific paper about it? Simply an amount people have observed as working in most situations? Cynically is it perhaps just the largest 'minimum' us hobbyists could stomach or be convinced of?

I mean fish can't count right - and surely 6 Corydoras in a 20 gallon might all hang out but 6 Corydoras in an 800 gallon might not even be aware of each others existence. And 1 in 6 odds of not dying to a predator wouldn't make me feel very particularly safe. 

To be clear I'm only curious not doubtful, it's almost more of a question of understanding the history of the hobby and where the number 6 came from than anything else. Oh and sorry if this topic has been done, just trying to start an interesting conversation and hear others insights!

[xXInkedPhoenixX]

@KentFishFanUK I agree with your thoughts on this and have never seen anything specific about WHY this is usually a minimum number. It might be when there is significant change in fish behavior. I've noticed though- that's a place TO START. For example, my black neons, when they dwindled their numbers down to 6 from 10 they acted more skittish. When I brought them back up to 10 they acted more confident- but I would bet if I got 5-10 more they would be even better (if only my tank size would accomodate). My Otos- in my parent tank I have about 10-14 (I don't see them often to do a proper count- they come out at night) they do all hang out mostly together but funnily enough they don't shoal nearly as much as the 60 I have being raised in my grow out tank. 

[Bobbie]

Yeah, I’ve always wondered why 6 is the minimum - and I’ve also often seen folks say that you should always try to have an odd number of fish, again I don’t know why. 
 

I’ve also noticed the behaviour change, when my zebra danios slowly died off and I was left with 3 instead of 7 there was a drastic change in fish behaviour with every death. Once I’d added the new fish and the number went up to 10 the danios were so different. 

[KentFishFanUK]

On 7/8/2021 at 11:35 PM, xXInkedPhoenixX said:

@KentFishFanUK I agree with your thoughts on this and have never seen anything specific about WHY this is usually a minimum number. It might be when there is significant change in fish behavior. I've noticed though- that's a place TO START. For example, my black neons, when they dwindled their numbers down to 6 from 10 they acted more skittish. When I brought them back up to 10 they acted more confident- but I would bet if I got 5-10 more they would be even better (if only my tank size would accomodate). My Otos- in my parent tank I have about 10-14 (I don't see them often to do a proper count- they come out at night) they do all hang out mostly together but funnily enough they don't shoal nearly as much as the 60 I have being raised in my grow out tank. 

Absolutely I totally agree it's the place to start, just wondered why we ended up there as the starting point. Often people say the same as you that their🤦‍♂️ school hid all the time until they had say 10, or 12 or whatever - so how comes 10 isn't the minimum? Similarly others say that a lower number worked for them. Maybe just years of hobbyists comparing notes reached 6 as the number most saw their fish get more active.

I have to admit though that when I went from 4 to 6 panda corydoras there was no appreciable difference in behaviour (at least to my inexperienced eyes). Even when they were only 4 they were super active and not shy or skittish, spending all day snuffling around like they do (so cute could watch them for hours). I still increased their number to 6 after a week or so as that was what I had planned for (to be honest they are such a joy to watch if I had the space I'd happily double that number over getting something else in) but it didn't make any difference to their behaviour - there was just more of them doing it. 

I have a sneaking suspicion that having the right set up (maybe not too bright lights, shade, floating plants, hiding places, substrate colour etc) and even things like time of day/night might have more to do with their behaviour than strictly group size. My lights aren't bright plus I have floating plants and moderate to heavy planting in the tank, wood and rocks and a dark substrate and so maybe I accidentally made an environment they felt safer in regardless of numbers? This is probably different from species to species and even between individuals so maybe wouldn't work all the time but still gets me thinking. 

Although another thing I noticed was one of my cories (the biggest) that I had from the start seems to be even more outgoing and confident etc than the rest, the others seem to almost follow it's lead so maybe I just got lucky and got a really brave fishy and that rubs off on the rest of them in a typical herd mentality kind of way. 

Then again I only added my (8) neon tetras today so what do I know! Just find it all so fascinating. pan widget

Edited July 8, 2021 by KentFishFanUK
There their they're

[Guppysnail]

2 girls for each boy 2 sets is where 6 comes from as a start point. 
 

two girls for every boy lalalala … beach boys 🤣

[KentFishFanUK]

On 7/8/2021 at 11:50 PM, Bobbie said:

Yeah, I’ve always wondered why 6 is the minimum - and I’ve also often seen folks say that you should always try to have an odd number of fish, again I don’t know why. 
 

I’ve also noticed the behaviour change, when my zebra danios slowly died off and I was left with 3 instead of 7 there was a drastic change in fish behaviour with every death. Once I’d added the new fish and the number went up to 10 the danios were so different. 

I think the odd number thing is something to do with spreading out aggression? Though I can only think that makes 3 better than 2, can't work out why 3 would ever be better than 4 for example. But then we are getting into the realms of mathematics and my brain just doesn't compute haha. 

Interesting about the Danios! Care to describe what about their behaviour changed? I don't know much about danios but I guess I just always pictured them zooming about regardless of group size haha. Was it a linearly gradual change to behaviour as each died off or did you notice a bigger change at certain numbers? i.e. did you happen to notice if going from 7 to 6 wasn't much change but 6 to 5 was a big difference? Or was going from 6 to 5 the same effect as 7 to 6?

Basically I'm curious if you noticed anything special about the number 6 I guess? Or any other number for that matter. 

[KentFishFanUK]

On 7/9/2021 at 12:18 AM, Guppysnail said:

2 girls for each boy 2 sets is where 6 comes from as a start point. 
 

two girls for every boy lalalala … beach boys 🤣

Haha! 

And yeah makes sense if you want two boys but why not just one boy and two girls for total of 3 as a starting point then? And increase by increments of 3?

Do the boys need the competition to reach their full potential maybe? That could certainly be one explanation. 

[Guppysnail]

On 7/8/2021 at 7:20 PM, KentFishFanUK said:

I think the odd number thing is something to do with spreading out aggression? Though I can only think that makes 3 better than 2, can't work out why 3 would ever be better than 4 for example. But then we are getting into the realms of mathematics and my brain just doesn't compute haha. 

Interesting about the Danios! Care to describe what about their behaviour changed? I don't know much about danios but I guess I just always pictured them zooming about regardless of group size haha. Was it a linearly gradual change to behaviour as each died off or did you notice a bigger change at certain numbers? i.e. did you happen to notice if going from 7 to 6 wasn't much change but 6 to 5 was a big difference? Or was going from 6 to 5 the same effect as 7 to 6?

Basically I'm curious if you noticed anything special about the number 6 I guess? Or any other number for that matter. 

The odd number is so when one female is close to delivering or in laying the other is a distraction so it does not stress the gravid one. the male will also overbreed the lone female and it is too taxing. I keep minimum 4 girls 1 boy. 

[Guppysnail]

On 7/8/2021 at 7:24 PM, KentFishFanUK said:

Haha! 

And yeah makes sense if you want two boys but why not just one boy and two girls for total of 3 as a starting point then? And increase by increments of 3?

Do the boys need the competition to reach their full potential maybe? That could certainly be one explanation. 

3 is enough if they are shoaling fish. If they are schooling 6 due to safety in groups. They wont “school” behavior display. 

Edited July 8, 2021 by Guppysnail
Spellings

[xXInkedPhoenixX]

@Guppysnail the boy/girl logic is a MAYBE especially when there are tried and true breeding practices with fish that have distinctive male/female markings- but plenty of us, myself included have fish that's not so easy to tell- especially when they're smaller. I have 10 Harlequins and 10 Black Neons, countless Otos. I can't tell boys from girls for the most part- only guess. 

[Guppysnail]

On 7/8/2021 at 7:28 PM, xXInkedPhoenixX said:

@Guppysnail the boy/girl logic is a MAYBE especially when there are tried and true breeding practices with fish that have distinctive male/female markings- but plenty of us, myself included have fish that's not so easy to tell- especially when they're smaller. I have 10 Harlequins and 10 Black Neons, countless Otos. I can't tell boys from girls for the most part- only guess. 

I understand completely. I got 8 CPD fry before sexing was viable and ended up with 3 girls 5 boys. They are fine and happy. That is just the logic behind those numbers and when possible i go for 4-1

Edited July 8, 2021 by Guppysnail
Spelling again

[KentFishFanUK]

On 7/9/2021 at 12:26 AM, Guppysnail said:

3 is enough if they are shoaling fish. If they are schooling 6 due to safety in groups. They wont “school” behavior display. 

You may be right but most people seem to advise minimum 6 even for shoaling fish. Maybe its because of the confusion between the difference? 

I've also heard reports that if you want to see schooling from a species that does that then you need way more than 6 for the most part so still doesn't explain the magic number really. 

[Guppysnail]

On 7/8/2021 at 7:32 PM, KentFishFanUK said:

You may be right but most people seem to advise minimum 6 even for shoaling fish. Maybe its because of the confusion between the difference? 

I've also heard reports that if you want to see schooling from a species that does that then you need way more than 6 for the most part so still doesn't explain the magic number really. 

I dont keep schooling fish any longer. Ive given up my extent of knowledge on the number thing. Someone with more knowledge will have to take it from here. Sorry

[KentFishFanUK]

On 7/9/2021 at 12:35 AM, Guppysnail said:

I dont keep schooling fish any longer. Ive given up my extent of knowledge on the number thing. Someone with more knowledge will have to take it from here. Sorry

Don't be sorry I'm totally only guessing/thinking out loud! The whole point was to invite discussion so thanks for replying in the first place! I appreciate the input 🙂

[xXInkedPhoenixX]

@Guppysnail why'd you give up the schoolers?

[Guppysnail]

On 7/8/2021 at 7:39 PM, KentFishFanUK said:

Don't be sorry I'm totally only guessing/thinking out loud! The whole point was to invite discussion so thanks for replying in the first place! I appreciate the input 🙂

No problem. My personal opinion is $. Ive kept sets of 3 2-1 schooling fish in the past without shyness or issues and they bred fine. Fish stores always want more sales. But that is just my experience and opinion i cant back it with fact. 

[xXInkedPhoenixX]

What I've noticed my Harlequins are ALWAYS in formation, even point the same direction. The Black Neons only school up when I approach the tank, otherwise they kinda do their own thing. 

[KentFishFanUK]

On 7/9/2021 at 12:31 AM, Guppysnail said:

I understand completely. I got 8 CPD fry before sexing was viable and ended up with 3 girls 5 boys. They are fine and happy. That is just the logic behind those numbers and when possible i go for 4-1

Just worked out what CPDs were, nice! Saw some today at the LFS for the first time and they are so lovely I am definitely going to have to try them sometime. I've seen pictures of them before but they don't do them justice somehow, they are like one of those fish you need to see with your own eyes to understand the appeal I think. 

[Guppysnail]

On 7/8/2021 at 7:39 PM, xXInkedPhoenixX said:

@Guppysnail why'd you give up the schoolers?

Personality need for attention i guess. I want fish to know and respond to me. My schoolers didnt know i existed or respond to my presence. Now guppies eat from my hand and CPDS RACE TO THE FRONT for food my plecos see me and sit like puppies each in their own food bowl. In other words crazy old lady nonsense 🤣

[Guppysnail]

On 7/8/2021 at 7:46 PM, KentFishFanUK said:

Just worked out what CPDs were, nice! Saw some today at the LFS for the first time and they are so lovely I am definitely going to have to try them sometime. I've seen pictures of them before but they don't do them justice somehow, they are like one of those fish you need to see with your own eyes to understand the appeal I think. 

My first run at cpd i had 2 g 1 boy. They did fantastic all by themselves 

[xXInkedPhoenixX]

@GuppysnailAHHH, totally get it, this is true. 

[KentFishFanUK]

On 7/9/2021 at 12:44 AM, Guppysnail said:

No problem. My personal opinion is $. Ive kept sets of 3 2-1 schooling fish in the past without shyness or issues and they bred fine. Fish stores always want more sales. But that is just my experience and opinion i cant back it with fact. 

You know what, I hadn't even considered the $ angle, but now I think about it it has to be a factor right, like both ways because they want to sell more fish but they also know if they told you you had to buy 100 of them they know noone would buy any so they have to give a reasonable/believable number. So yeah good point, it absolutely could be a marketing thing! 

[Guppysnail]

On 7/8/2021 at 7:51 PM, KentFishFanUK said:

You know what, I hadn't even considered the $ angle, but now I think about it it has to be a factor right, like both ways because they want to sell more fish but they also know if they told you you had to buy 100 of them they know noone would buy any so they have to give a reasonable/believable number. So yeah good point, it absolutely could be a marketing thing! 

Yup i also kept an extremely happy albino cory alone and it was happy and interacted with me in a betta tank with neon tetras snails and shrimp. Long story on that odd combo but everyone was very healthy and happy

[xXInkedPhoenixX]

True about the $, kind of like you have to have a heater. 

[xXInkedPhoenixX]

@Guppysnail I've had a solo albino cory in my lifetime as well.