# Stocking guidelines



## JonRivers (25 Aug 2019)

Hi,

Are there any general rules of thumb for stocking of planted tanks?

I appreciate the ethical side of the hobby in terms of length of fish vs tank size.

Many thanks!


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## Matt @ ScapeEasy (25 Aug 2019)

I've always worked with the 1cm per litre rule as a rough guide. Stocking up to about 75% capacity max (any more looks too visually full to me). 

More accurately... I keep an eye on nitrate levels and keep them in check between water changes. 

Technically with plants you can stock more fish yes, but personally I would not exceed the normal levels... what if you miss a ferts dose or you lights fail etc etc. I do not think it would be ethical to cram in more fish just because there are plants.


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## tam (25 Aug 2019)

Matt @ ScapeEasy said:


> I've always worked with the 1cm per litre rule as a rough guide.



Do you mean that or did you accidentally change it converting to metric? Usually the 'common' rule is an inch per gallon e.g. a 50L / 11g tank would be 11" (28cm) of fish not 50cm (20")? Although if you then knock 25% off you probably end up closer to the same place 

It works ok as a rough rule for small fish that aren't weirdly shaped - obviously you wouldn't put a single 11" long fish in a 50L tank.

You want to look at behaviour as well and tank shape. Fish that are rapid dashers might be unsuitable for a tall narrow tank but ok with a long low one of the same volume.

It's hard to make general rules as they'll always be a fish that breaks them.


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## Matt @ ScapeEasy (26 Aug 2019)

tam said:


> Do you mean that or did you accidentally change it converting to metric? Usually the 'common' rule is an inch per gallon e.g. a 50L / 11g tank would be 11" (28cm) of fish not 50cm (20")? Although if you then knock 25% off you probably end up closer to the same place



It's weird how the rule changes around the world dependant on whether you are in litres or gallons! No conversion errors here, I just work in litres and find stocking to no more than 75% (using that rule) is my comfortable maximum. Any more and I suggest more frequent/bigger water changes than my 50% per week. Maybe I should switch to 28cm per 50 litres... just checked my stocking level currently against this rule and it's just shy of 100% at what would be 55ish%... happy with that!



tam said:


> You want to look at behaviour as well and tank shape. Fish that are rapid dashers might be unsuitable for a tall narrow tank but ok with a long low one of the same volume.



Agreed, most good fish profiles will include a minimum tank length too.



tam said:


> Do you mean that or did you accidentally change it converting to metric? Usually the 'common' rule is an inch per gallon e.g. a 50L / 11g tank would be 11" (28cm) of fish not 50cm (20")? Although if you then knock 25% off you probably end up closer to the same place
> 
> It works ok as a rough rule for small fish that aren't weirdly shaped - obviously you wouldn't put a single 11" long fish in a 50L tank.
> 
> ...



As previous though, I believe monitoring nitrate levels is the best indication of whether you have appropriate stocking. Rather than a rule, use what you can observe about your tank.


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## Matt @ ScapeEasy (26 Aug 2019)

Returning to add... ive found reference to 4 cms per gallon lol...

I've also found an English source referring to stock to the 1 inch per gallon for the first 6 months of a newly set up tank which is an interesting factor to add to this debate. Can a more mature tank support more fish? My immediate reaction is no... once the tank can come with an ammonia load it can cope with an ammonia load (I also don't want to get side tracked into cycling debates!) however i think there is probably some reasonable observed evidence to say that some fish do appear to fair better in a more established tank. So this should be a consideration too if setting up a new tank afresh.

*I return to monitoring nitrate levels as the best "rule" for stocking* however there are always other factors such as your fish length and this tank maturity.  This "rule" also helps answer the question as to what water changes you should be doing as a minimum.


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## Edvet (26 Aug 2019)

Basically it's a function of waterquality more then anything else. When coupled with lots of healthy plants or a realy sturdy filtersystem you can go over that. I've seen discus jampacked in a small tank, but with a huge filtersystem behind it.


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## Matt @ ScapeEasy (26 Aug 2019)

Agreed! This is the situation we find in fish stores too.  But would this give the discus enough "room to be comfortable" long term? I guess is a question we will never be able to scientifically answer, unless we learn to speak fish.

Also now realising that fertilisation needs to be mentioned here seeing as we are talking about planted tanks... If stocking is a function of water quality and I'm using nitrate as an indicator of this. The amount you fertiliser has to come into play. I know that I've previously overdosed a complete fertiliser (though I was only following the instructed dose rate, I had mainly slow growing plants) resulting in very high nitrate levels. First noticing this when my Amano shrimp were behaving differently. 

By using this same methodology of testing nitrate you can also aim to get your fertilisation dose dialled in.  Of course if you are dosing individually dry salts this is obvious to you. For the layperson perhaps not so much so...

My personal preference here is to combine the convenience of pre mixed ferts with the option to dial things in by using both a complete and a micro fertiliser. I test nitrate to understand how much complete fertiliser to use which I dose to reach an acceptable post water change level of nitrates given how they will rise before the next water change. I then 'top up' with my micro fertiliser to ensure there is enough iron (my chosen indicator for micro availability) in the water prior to the end of week water change.


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## Edvet (26 Aug 2019)

Discus prefer to group up so i think they enjoyed it.
Nitrates are very low in toxicity, EI levels should never be a problem , nitrates as a result from ammonia ( very toxic) -nitrites (very toxic)- nitrates very low toxicity can be a problem with the precursors.


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## zozo (26 Aug 2019)

I would simply setup and scape the tank, let the plants go through transition and grow in. From there forget the lenght per volume rule. Because it's not only ancient, it's commercialy based guidline. As said above by @Edvet  volume says nothing about how well the setup can coop with the organic pressure and maintain water quality.

Bottom line every fish tank no matter how it's setup up it's a Diorama, a little "Art"ificial under water world the way you like to look at it. Than rather use proper scaling and how well the fish you choose compliment the setup and still live a happy active live. Not only looks and size but also behaivor and compatibilty. Not only compatibility between the fish spp. themselfs but also towards the biological capacity of the setup and how much maintenance are you able to perform on a weekly or even daily basis.

Review questions regarding the fish, what does it like/requires?.. Diet? Light penetration, Shelter and how should thise be provided, plants or caves? Free swiming space and where does it like to swim, lower, middle or upper region? Is it an active or a passive swimmer, does it school, schoal, pair up or is it rather solitairy. What is the teritorial demand/behaivor among eachother and others. Is it an closed or open top setup, does the fish like to jump? Than this fish is not suitable for an open top. Etc etc.

Than if you have a desired fish spp. in mind before you start setting up a tank. Than research the fish and build a tank that fits their requirments. Than if you don't know, than setup up a tank, let it grow in and decide from there what compliments this scape the best.

Than when it comes to size, there is no actual rule.. It's simply common sense and how you like to see it personaly.
My personal take on it is, a fish needs traveling space and broken lines of sight. To give it this sufficiently in make sure it can swim it's own lenght at least 20x traveling from left to right and 10x from front to back.  My tank is 35x35x90cm thus my limit is it should not be larger than 35mm, preferably smaller. It not only scales beter into the dimension it also looks happier and more natural.

I know people that use the 1cm/L formula and put a 12cm solitairy fish in a 80x35x35 cm tank and proudly and happily present it like that. They don't think for themself only live up to the given rules from abook and think its ok. But don't see the fact that this fish wiggles its tail 3 times and than bumps its nose into the next glaspanel and needs to turn 180°. If it gets excited it realy bumps into all 4 panels in less than 2 seconds. For me personlay, it's a fish in a jail cell punished for life.  I feel sorry for it.


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## Matt @ ScapeEasy (26 Aug 2019)

Edvet said:


> Discus prefer to group up so i think they enjoyed it.
> Nitrates are very low in toxicity, EI levels should never be a problem , nitrates as a result from ammonia ( very toxic) -nitrites (very toxic)- nitrates very low toxicity can be a problem with the precursors.



Problem was at the rate I was dosing with my slow growing plants, there was always some left over at the end of the week, even post a big water change, so they just built up and up over time and got into the many hundreds of ppm... I didn't know better at the time and wasn't regularly testing (from my pre fertilisation days there never seemed any need) once I tested of course the problem became apparent!


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## tam (26 Aug 2019)

Matt @ ScapeEasy said:


> It's weird how the rule changes around the world dependant on whether you are in litres or gallons!



I think it might be time as well as location. The rule pre-dates the UK swapping from imperial - my fish interest comes from my parents who would have started when the UK was still using/used to gallons and inches and so did the old fish books/magazines I read as a kid did too. The internet is post the swap to metric so you're more likely to find UK references to litres and cm. I would guess at some point someone did a bad conversion of the rule to cm/L and then as things do it got copied and repeated.


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## JonRivers (26 Aug 2019)

Nice little conversation this has started!

I really appreciate the input from each of you.



zozo said:


> I would simply setup and scape the tank, let the plants go through transition and grow in. From there forget the lenght per volume rule. Because it's not only ancient, it's commercialy based guidline. As said above by @Edvet  volume says nothing about how well the setup can coop with the organic pressure and maintain water quality.
> 
> Bottom line every fish tank no matter how it's setup up it's a Diorama, a little "Art"ificial under water world the way you like to look at it. Than rather use proper scaling and how well the fish you choose compliment the setup and still live a happy active live. Not only looks and size but also behaivor and compatibilty. Not only compatibility between the fish spp. themselfs but also towards the biological capacity of the setup and how much maintenance are you able to perform on a weekly or even daily basis.
> 
> ...




Thanks to Zozo. This is the sort of advice that should be being given out by LFS's.


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## sparkyweasel (26 Aug 2019)

If you look back  even further than the change to metric, older books often recommended stocking based on the surface area, rather than the volume. Before we had efficient filters giving good circulation, gas exchange at the surface was considered most important.


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## Edvet (26 Aug 2019)




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## JonRivers (26 Aug 2019)

That's one way to do it Edvet, not sure its tho right way though! haha


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## zozo (26 Aug 2019)

JonRivers said:


> That's one way to do it Edvet, not sure its tho right way though! haha



Well the graphic dates from the same era as 1cm fish per litre guide. That would equal 2 x 110cm pikes in a 250 litre and decorated tank.
And i wouldn't like to buy a meal for each person still taking this serious. I guess it'll cost me a lifetime salery iin a day.


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## zozo (26 Aug 2019)

JonRivers said:


> This is the sort of advice that should be being given out by LFS's



They are in it for the money.. And if they would be realy that honest people will walk away and go to places that tell what they want to hear and spend their money there. That's how the majority works. In the pet industry sales, you'll shoot your own foot with beeing truthful. Thus half truth is good enough the rest is the customers responsibility.

In a way it is a shared responsibility. It is very time consumming to ask every single customer if he knows what he's doing.. Only thing is, the LFS wrongfully present themselfs as experts. They are indeed expert in tryng to make easy as possible money in the first place.


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## JonRivers (26 Aug 2019)

Totally agree mate, if definitely doesn't only apply to the fish world.

At least with tropical most fish are tank raised and it's all they have known.


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## DeepMetropolis (26 Aug 2019)

http://www.aqadvisor.com/ this is what I use just to see what's reasonable..


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## Matt @ ScapeEasy (26 Aug 2019)

tam said:


> I think it might be time as well as location. The rule pre-dates the UK swapping from imperial - my fish interest comes from my parents who would have started when the UK was still using/used to gallons and inches and so did the old fish books/magazines I read as a kid did too. The internet is post the swap to metric so you're more likely to find UK references to litres and cm. I would guess at some point someone did a bad conversion of the rule to cm/L and then as things do it got copied and repeated.



Good point! I once did an article on another forum where I compared an old fishkeeping book to my understanding of modern 'best-practise" which made for interesting reading...  I'm sure there would be even more changes on aquascaping over the same time period!


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## dw1305 (26 Aug 2019)

Hi all,
I just go on the maxim _does the tank look busy?_ If it does your fish are too large, or you have too many of them, or you don't have enough plants. Having your tank "under-stocked" makes it more likely that you will get fry surviving, less likely you will have territorial issues and more resilient in terms of  a disaster like chloramine in your water, or a dead fish, or filter failure etc.

For a 60cm tank I have just a pair of dwarf cichlids, some dithers and a lot of plants and structure. It sounds like it won't be very exciting and visitors often ask _where are the fish? B_ut you only need to wait for a few seconds and the fish will appear behaving in a non-stressed manner.

cheers Darrel


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## alto (26 Aug 2019)

I have too many S osphromenoides in one tank - I special ordered and it was a bag lot - and the tank can still look empty 

30 juveniles in a 60cm x 45 x 55 planted tank


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