How many fish are too many?

eatbreakfast · 02/06/2014, 07:37 AM

While reading through threads all too often the comments are seen that tanks have too many fish or that a tank is overcrowded. So my question is to all who say that, or anyone else for that matter, how many fish are too many?

Now I know there are many factors that go into that statement, tank volume, tank surface area, type of fish, swimming space, etc. But there should be some evidence or metric to point to whether the tank is 5g or 5000g.

So what are we looking for? Is it water chemistry? aggression? oxygen content?

Please chime in. I am interested in what everyone has to say regarding this.

trueperc · 02/06/2014, 07:42 AM

One key factor is the water chemistry as in nitrates and phospates. If filtration can't keep up with maintaining theses at low to almost zero levels then you have to much bio load as in to many fish. I have a 300 gallon and am right now in the process of removing some fish because I can not get my levels down to acceptable for a sps reef. This is even after trying many things to add to the filtration. As David Saxby one said in his videos, the key to this hobby is we keep water. Mean water quaility is what is most important.

thegrun · 02/06/2014, 08:33 AM

The reason there is no set rule is that there are too many variables. The size and type of skimmer, does the tank have a refugium, deep sand bed, bioreactor, water flow...the list goes on and on. On the chemical side nitrates and phosphates need to be kept in check. On the livestock side are fish compatible (even this is a variable as there are big differences from fish to fish within a given species) and what are their swimming requirements?

Metal Man 1221 · 02/06/2014, 08:35 AM

This has often been a touchy subject. But trueperc is absolutly right. If the fish foul the water, and your equipment and maintainence cant keep up, then thats the biggest give away that you have too many fish.

But I dont think there is a single, let alone simple, method of determining just how many fish are too many.

downbeach · 02/06/2014, 08:38 AM

Here's one person's thought process.

02/06/2014, 07:37 AM	#1
eatbreakfast Registered Member Join Date: May 2010 Location: seymour, ct Posts: 1,636	How many fish are too many? While reading through threads all too often the comments are seen that tanks have too many fish or that a tank is overcrowded. So my question is to all who say that, or anyone else for that matter, how many fish are too many? Now I know there are many factors that go into that statement, tank volume, tank surface area, type of fish, swimming space, etc. But there should be some evidence or metric to point to whether the tank is 5g or 5000g. So what are we looking for? Is it water chemistry? aggression? oxygen content? Please chime in. I am interested in what everyone has to say regarding this.

02/06/2014, 08:35 AM	#4
Metal Man 1221 FMMAS Executive Director Join Date: Aug 2009 Location: Fargo ND Posts: 1,504	This has often been a touchy subject. But trueperc is absolutly right. If the fish foul the water, and your equipment and maintainence cant keep up, then thats the biggest give away that you have too many fish. But I dont think there is a single, let alone simple, method of determining just how many fish are too many. __________________ "My advise is, always look at their aquarium before you take their advise. Because alot of people give advise and they havnt got a clue" ~David Saxby~ "Only after the last tree's cut and the last river poisoned only after the last fish is caught will you find that money cannot be eaten" ~Lamb of God~ Current Tank Info: 125g DT, 45g sump ---- 57g Illuminata, custom sump

02/06/2014, 07:42 AM	#2
trueperc Registered Member Join Date: Feb 2003 Location: Ottawa, On, Canada Posts: 788	One key factor is the water chemistry as in nitrates and phospates. If filtration can't keep up with maintaining theses at low to almost zero levels then you have to much bio load as in to many fish. I have a 300 gallon and am right now in the process of removing some fish because I can not get my levels down to acceptable for a sps reef. This is even after trying many things to add to the filtration. As David Saxby one said in his videos, the key to this hobby is we keep water. Mean water quaility is what is most important.

02/06/2014, 08:33 AM	#3
thegrun Registered Member Join Date: Dec 2008 Location: Garden Grove, Ca Posts: 17,023	The reason there is no set rule is that there are too many variables. The size and type of skimmer, does the tank have a refugium, deep sand bed, bioreactor, water flow...the list goes on and on. On the chemical side nitrates and phosphates need to be kept in check. On the livestock side are fish compatible (even this is a variable as there are big differences from fish to fish within a given species) and what are their swimming requirements?

02/06/2014, 08:38 AM	#5
downbeach Registered Member Join Date: Nov 2006 Location: Smyrna, Delaware Posts: 3,767	Here's one person's thought process.