I often see / hear people asking what I can fit in my tank or what size tank would be good for a certain fish. Sometimes the responses they receive are all over the place and often times just confusing to me.
So lets talk about what makes a certain tank size appropriate. Here is the questions I need to answer before determining tank size:
1. What is the max length the fish will likely reach?
2. how active is the fish?
3. where would the fish be found in the wild?
4. will there be tank mates?
5. what is the bio-load of the like?
As an example I will look at some fish that I have experience with.
Cardinal Tetra
Now lets answer the questions:
1. 1.5-2" max
2. not really active
3. densely planted areas or in dense coverage, murky water, hiding due to their bright coloration
4. in this case lets assume no other tank mates
5. low bioload, slim fish doesn't need to eat a whole lot due to its size and activity level.
I know these fish like to be in groups, bigger is better but since they often loosely shoal in cover they simply don't need a long / big aquarium to swim laps in. a group of 20 cardinals will easily be fine in a 24" length tank 12" tall 12" wide. I wouldn't hesitate to go as small as 12-16" length tank either. In aquaria they act as they do in the wild. hide most of the time.
Something to note is that smaller tanks are cheap and often times we will buy something bigger because its only a few bucks more. its often the case in smaller tanks to have a length of 10-20 times longer than the fish kept in the tank. If we use these numbers with keeping larger fish we would realize that we are way off the mark in terms of length. But its simply not needed to always have that sort of length unless the fish requires it.
Here is another smaller fish but with completely different needs.
praecox rainbow
1. 2" max
2. very active
3. planted areas, more open swimming areas
4. no tank mates
5. low bio load more than the cardinal due to body shape (mass)
again these fish like to be in a school. i would say 6-12 is a good number to start with. tank could be 12" tall, 12" wide, but I would like to suggest 36" minimum length, maybe even 48" would be better. These fish will happily do laps and use the full length of that swimming space. while you could look at the size of the fish and make an assumption that the length is the same as the cardinal tetra so therefore they can be in a similar size aquarium. they could fit but not really be happy long term with limited swimming space.
I think we need to apply this kind of thought process with our big monster we keep. as a bare minimum for tank height I would like to see at least 2 - 3 times the height of the fish. for width you would look for a minimum of 2-4" longer than the length of the fish at full size. This will ensure the fish can turn around comfortably. For length we can look at the questions I have above to help us with the decision making.
What do you guys/gals think?
for an active open water type of fish, what length of tank would you like to see? 10x the length of the adult fish? 4x? 20x? what is your idea of the right length?
So lets talk about what makes a certain tank size appropriate. Here is the questions I need to answer before determining tank size:
1. What is the max length the fish will likely reach?
2. how active is the fish?
3. where would the fish be found in the wild?
4. will there be tank mates?
5. what is the bio-load of the like?
As an example I will look at some fish that I have experience with.
Cardinal Tetra
Now lets answer the questions:
1. 1.5-2" max
2. not really active
3. densely planted areas or in dense coverage, murky water, hiding due to their bright coloration
4. in this case lets assume no other tank mates
5. low bioload, slim fish doesn't need to eat a whole lot due to its size and activity level.
I know these fish like to be in groups, bigger is better but since they often loosely shoal in cover they simply don't need a long / big aquarium to swim laps in. a group of 20 cardinals will easily be fine in a 24" length tank 12" tall 12" wide. I wouldn't hesitate to go as small as 12-16" length tank either. In aquaria they act as they do in the wild. hide most of the time.
Something to note is that smaller tanks are cheap and often times we will buy something bigger because its only a few bucks more. its often the case in smaller tanks to have a length of 10-20 times longer than the fish kept in the tank. If we use these numbers with keeping larger fish we would realize that we are way off the mark in terms of length. But its simply not needed to always have that sort of length unless the fish requires it.
Here is another smaller fish but with completely different needs.
praecox rainbow
1. 2" max
2. very active
3. planted areas, more open swimming areas
4. no tank mates
5. low bio load more than the cardinal due to body shape (mass)
again these fish like to be in a school. i would say 6-12 is a good number to start with. tank could be 12" tall, 12" wide, but I would like to suggest 36" minimum length, maybe even 48" would be better. These fish will happily do laps and use the full length of that swimming space. while you could look at the size of the fish and make an assumption that the length is the same as the cardinal tetra so therefore they can be in a similar size aquarium. they could fit but not really be happy long term with limited swimming space.
I think we need to apply this kind of thought process with our big monster we keep. as a bare minimum for tank height I would like to see at least 2 - 3 times the height of the fish. for width you would look for a minimum of 2-4" longer than the length of the fish at full size. This will ensure the fish can turn around comfortably. For length we can look at the questions I have above to help us with the decision making.
What do you guys/gals think?
for an active open water type of fish, what length of tank would you like to see? 10x the length of the adult fish? 4x? 20x? what is your idea of the right length?
