The 1 inch per gallon rule
- Thread starter Dragon cqzzzzz<
- Start date
As your subject line says...one inch of fish for every gallon of water.
So, if you laid all your fish end to end and measured, and say you got 72 inches, then you'd want a minimum 75 gallon tank, not taking into consideration growth.
In actuality, you'd probably want something closer to 100-150, depending on how big your fish will get.
So, if you laid all your fish end to end and measured, and say you got 72 inches, then you'd want a minimum 75 gallon tank, not taking into consideration growth.
In actuality, you'd probably want something closer to 100-150, depending on how big your fish will get.
What if the fish live in different levels of the tank. For instance, if my silver dollar becomes 6 inches long, my dragon fish gets to 15 inches, and the algae eater gets 6 or 7 inches. That brings my total to about 28 gallons, but the dragon fish lives on the bottom, the silver dollar in the middle, and the algae eater on the walls and bottom. Could't that somehow bring it down since they don't come into contact with each other very often?
Yeah its all about the bioload you're putting on your bacteria, not so much about the actual room in the tank for each fish, which also matters of course. A certain sized tank can only hold a certain amount of bacteria, which can only handle a certain amount of ammonia. If you have more fish and therefore more fish waste than the bacteria can handle, your ammonia, nitrite and nitrate levels may rish to harmful and fatal levels.
EDIT: - It doesn't matter how often you clean the tank- if you have too much waste being dumped into your tank, your water will be poisonous all the time.
EDIT: - It doesn't matter how often you clean the tank- if you have too much waste being dumped into your tank, your water will be poisonous all the time.
The only time you want to look at that rule is when you're using it as a guideline for setting up a tank (or seeing if there is more room left to add fish). Its only really useable with fish that stay under 3 inches or so, because larger fish, or very territorial fish (like cichlids) have different requirements so the inch per gallon rule isn't going to apply. To use it correctly you have to consider the adult size of the fish that you're getting (NOT the size they are now).
The fact that different fish like to occupy different space inside of the tank is a completely different factor in planning a tank....it has nothing to do with how many fish can fit into a tank because of the size of your bacteria colonies.
The fact that different fish like to occupy different space inside of the tank is a completely different factor in planning a tank....it has nothing to do with how many fish can fit into a tank because of the size of your bacteria colonies.
Wrong. Waste has to accumulate over time. Frequent water changes enable a substantial degree of overloading. Maintenance is intensive, but routine, with the frequency of water changes determined by the waste load.
RE: Plants adding to bioload
No. They add to dark-cycle oxygen demand. Their function of nutrient absorption can assist with maintaining tank parameters, but if you don't balance things right you can literally suffocate your fish with green plants. Additionally, keeping the nutrient balance stable in an overloaded tank through the use of plants is very, very difficult. Again, maintenance intensive, requiring significant attention being paid to tank parameters. Then there's natural attrition of old vegetation that has to be dealt with.
Froggy has it right with the <3". It's about bioMASS...emphasis on the mass...not simply length.
These are good questions, but far more than a beginner should be attempting.
RE: Plants adding to bioload
No. They add to dark-cycle oxygen demand. Their function of nutrient absorption can assist with maintaining tank parameters, but if you don't balance things right you can literally suffocate your fish with green plants. Additionally, keeping the nutrient balance stable in an overloaded tank through the use of plants is very, very difficult. Again, maintenance intensive, requiring significant attention being paid to tank parameters. Then there's natural attrition of old vegetation that has to be dealt with.
Froggy has it right with the <3". It's about bioMASS...emphasis on the mass...not simply length.
These are good questions, but far more than a beginner should be attempting.
I know that obviously water changes is going to help some, but if your tank is grossly overloaded, you'd have to do them almost constantly, since almost ANY ammonia is toxic. And I thought is was impossible to completely remove ammonia with water changes.
Also about the plants, I was talking about dead or rotting plant matter. Doesn't that ADD to the organic waste, along with fish poo and uneaten food, that the bacteria has to deal with?
I new at this, just trying to understand everything along with everyone else.
Also about the plants, I was talking about dead or rotting plant matter. Doesn't that ADD to the organic waste, along with fish poo and uneaten food, that the bacteria has to deal with?
I new at this, just trying to understand everything along with everyone else.
I'm a bit confused with all this. There is about 10 different questions floating about.
Plants help a tanks bio-load because they use some of the nitrates as food. In this way the nitrates won't build up to a toxic level as quickly, therefore not causeing any problems for the fish.They can theoredicly 'choke' a tank because during the day they absorb carbon dioxide (Co2) and release Oxygen (O2), however after lights out they switch this and absorb O2 and release Co2. This however takes a very large amount of plants, and not something that most people are going to have to worry about. An easy way to tell is to look at your fish in the mornings before the lights come on. If you see them at the surface gasping for air then you'll know that there isn't enough oxygen in the water at night. Running a simple air stone during night can quickly fix this problem.
For those still strugleing with the inch per gallon rule think of this: Would you want to put a full grown 12" oscar in a 12 gallon tank? It's not so much a rule as it is a guideline for small, non-teritorial fish. Nothing in this hobby is set in stone, and what works for one person may end up with terible results for another.
Plants help a tanks bio-load because they use some of the nitrates as food. In this way the nitrates won't build up to a toxic level as quickly, therefore not causeing any problems for the fish.They can theoredicly 'choke' a tank because during the day they absorb carbon dioxide (Co2) and release Oxygen (O2), however after lights out they switch this and absorb O2 and release Co2. This however takes a very large amount of plants, and not something that most people are going to have to worry about. An easy way to tell is to look at your fish in the mornings before the lights come on. If you see them at the surface gasping for air then you'll know that there isn't enough oxygen in the water at night. Running a simple air stone during night can quickly fix this problem.
For those still strugleing with the inch per gallon rule think of this: Would you want to put a full grown 12" oscar in a 12 gallon tank? It's not so much a rule as it is a guideline for small, non-teritorial fish. Nothing in this hobby is set in stone, and what works for one person may end up with terible results for another.
Hi Orion, great summary. However, I think we could add that plants also use ammonia and nitrites for food - which is one of the reasons cycling is so much milder in planted tanks. Plants basically use any nitrogen source (ammonia, nitrites, nitrates).
The 1-inch-per-gallon rule is definitely just a "guideline" and works for most smallish fish, but not for larger fish or messy fish - or for dwarf puffers (which need at least 3 gallons per DP). Goldfish need about 10-20 gallons each.
There is also the surface area calculation, which is good to use if stocking something like a Bi-Ube/Bi-Orb tank or a very tall tank.
(tank length x tank width) / 10 = inches of fish that can be stocked
Then there is the allowance made by having live plants, which suggests that stocking can exceed the "guidelines" by some percentage if the tank is lightly/moderately/heavily planted.
There are no set-in-stone rules, but just general guidelines that are especially helpful for newbies.
The 1-inch-per-gallon rule is definitely just a "guideline" and works for most smallish fish, but not for larger fish or messy fish - or for dwarf puffers (which need at least 3 gallons per DP). Goldfish need about 10-20 gallons each.
There is also the surface area calculation, which is good to use if stocking something like a Bi-Ube/Bi-Orb tank or a very tall tank.
(tank length x tank width) / 10 = inches of fish that can be stocked
Then there is the allowance made by having live plants, which suggests that stocking can exceed the "guidelines" by some percentage if the tank is lightly/moderately/heavily planted.
There are no set-in-stone rules, but just general guidelines that are especially helpful for newbies.
The one inch per gallon rule is a total approximation for beginners, becaue for a start when you get going you can use 2 inches per gallon.....
You might want to consider it's also got to do with the amount of dissolved oxygen available. One of the real joys of an overstocked tank, let alone all the waste management, is that on hot days, or if the power goes out, leaving all your bubblers and whatever useless, all your fish will come to the surface to gulp air, or some will die due to lack of oxygen.
You might want to consider it's also got to do with the amount of dissolved oxygen available. One of the real joys of an overstocked tank, let alone all the waste management, is that on hot days, or if the power goes out, leaving all your bubblers and whatever useless, all your fish will come to the surface to gulp air, or some will die due to lack of oxygen.