Stocking capacity question

Seb2502

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I have a 75 gallon planted aquarium stocked with the following…
Around 19 rummy nose tetras
15 ember tetras
15 Cardinal tetras
2 otocinclus
4 amano shrimp

I need to know if the tank is too heavily stocked or if I can fit more fish in there because I’m thinking of getting either Angel fish or discus
 

Colin_T

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How long has the tank been set up for?

What are the tank dimensions (length x width x height)?

What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

Depending on what the GH of your water is, will determine what fish you should keep.

Angelfish, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.

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How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate new water before adding it to the tank?

What sort of filter is on the tank?
How often and how do you clean the filter?

How often do you feed the fish?
What do you feed the fish?

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These factors all go into determining how many fish can be kept in an aquarium. A big tank with a few small fish might be fine if you only do a water change once a month or if they only get fed a small amount. If you have bigger fish and feed heavily, you might be overstocked.

You need to monitor the nitrate levels and if they don't change between water changes, and the fish have space to move without running into each other, then it's probably not overstocked.
 
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Seb2502

Seb2502

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How long has the tank been set up for?

What are the tank dimensions (length x width x height)?

What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

Depending on what the GH of your water is, will determine what fish you should keep.

Angelfish, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.

-----------------------
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate new water before adding it to the tank?

What sort of filter is on the tank?
How often and how do you clean the filter?

How often do you feed the fish?
What do you feed the fish?

-----------------------
These factors all go into determining how many fish can be kept in an aquarium. A big tank with a few small fish might be fine if you only do a water change once a month or if they only get fed a small amount. If you have bigger fish and feed heavily, you might be overstocked.

You need to monitor the nitrate levels and if they don't change between water changes, and the fish have space to move without running into each other, then it's probably not overstocked.
Tank has been up for 7 months now
48” x 18” x 19” are the dimensions
gH is around 10 ppm
kH is 250 ppm
pH is 7.5-7.8
Nitrates is at 10 ppm
Nitrites is 0ppm
Ammonia is 0ppm
I water change 20% twice a week
I gravel vac every other water change
Yes I dechlorinate

It has a sponge filter and it’s cleaned every 3 months
The fish are fed flakes once to twice a day
Nitrates and ammonia and nitrites don’t change
 

Colin_T

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I would clean the filter once a month and do bigger water changes (50-75%) once a week. It will dilute disease organisms better than a 20% water change twice a week.

Your tank isn't overstocked currently and you could add more fish. However, discus really need a bigger tank (4x2x2ft minimum), and angelfish might eat the ember and cardinal tetras.

You could add a pair of dwarf cichlids like Apistogramma cacatuoides or something else that is similar. Or maybe a small species of gourami (not dwarf gouramis - Colisa lalius though because they are riddled with diseases that can't be cured). If you don't want dwarf cichlids, then maybe a group of Corydoras.
 

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I agree with Colin. Cories however need sand, so keep that in mind. And if you stay with smallish shoaling fish, you can have double or triple the numbers. Stocking is less about mass/volume and more about providing what the individual species need, as this has less impact on the biological system because it avoids stress which weakens fish.

Are the nitrates occurring in the source (tap) water, or within the tank? If the latter, lowering them is advisable, as close to zero as possible. And are there live plants?
 
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Seb2502

Seb2502

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I agree with Colin. Cories however need sand, so keep that in mind. And if you stay with smallish shoaling fish, you can have double or triple the numbers. Stocking is less about mass/volume and more about providing what the individual species need, as this has less impact on the biological system because it avoids stress which weakens fish.

Are the nitrates occurring in the source (tap) water, or within the tank? If the latter, lowering them is advisable, as close to zero as possible. And are there live plants?
The nitrates come from within the tank I believe. The tank has many live plants and I’ve started dosing with iron
 

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The nitrates come from within the tank I believe. The tank has many live plants and I’ve started dosing with iron

Do not single dose nutrients, especially iron. If you need a plant additive, use a comprehensive so all 17 nutrients are available. Iron is a micro-nutrient, and a heavy metal. I killed my floating plants twice by using iron in addition to a comprehensive.

You should be able to get nitrates lower, as close to zero is best for fish. You are no where near "over stocked" so that means fish are either being fed too much, or the organics are not being removed sufficiently. Plants use ammonia/ammonium, not nitrate (unless you are running a high-tech system).
 
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Seb2502

Seb2502

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Do not single dose nutrients, especially iron. If you need a plant additive, use a comprehensive so all 17 nutrients are available. Iron is a micro-nutrient, and a heavy metal. I killed my floating plants twice by using iron in addition to a comprehensive.

You should be able to get nitrates lower, as close to zero is best for fish. You are no where near "over stocked" so that means fish are either being fed too much, or the organics are not being removed sufficiently. Plants use ammonia/ammonium, not nitrate (unless you are running a high-tech system).
So it’s better to get a complete fertilizer?
I think I might be feeding them a bit too much. There’s so many of them and they’re always swimming in the front of the glass and following me till I feed them
 

Byron

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So it’s better to get a complete fertilizer?

Yes. Aquatic plants require 17 nutrients, some occur naturally (oxygen, hydrogen and carbon), some may come in with water changes (depending upon the GH of your tap water), others come from fish foods that get digested and the waste is then broken down in the substrate by various bacteria. In a tank with a decent fish load, with slow-growing plants (these need less nutrient), this can be self-sustaining. But most of us want more demanding plants and that is where supplements are needed.

The other thing about nutrients is that they need to be in relative proportions to each other. Too much of nutrient "x" might (depending upon the nutrient) cause plants to shut down assimilation of nutrient "y" or similar. For example, excessive iron will reduce the uptake of manganese, creating a deficiency. The quality comprehensive supplements should never cause such problems, unless overdosed.

Seachem's Flourish Comprehensive Supplement and their Flourish Tabs are high quality, I have had success for over a decade. In the UK, TNC Lite is much the same. There are undoubtedly others, but these are readily available for most members on TFF.

If your water is very soft (GH close to zero as mine is) there may be a need for additional calcium and magnesium, as these are minimal in the comprehensives since many have sufficient in the source water. I experimented for several years over this, and there are remedies.
 

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I think I might be feeding them a bit too much. There’s so many of them and they’re always swimming in the front of the glass and following me till I feed them

This is a common mistake many of us made at one time. Fry need more frequent feedings, but mature fish can manage with less. In nature considerable energy is needed to find food--not in the aquarium. Fish are ectotherms, meaning they do not generate their internal heat so that takes much less energy (food) than one might expect. One feeding a day is more than sufficient, and a small feeding at that. Fish are programmed to search for food in order to reproduce and maintain the species. In their habitats, they may go days without finding any, so they naturally tend to eat everything they do find. In the aquarium this can be disastrous.

Missing one, two or three days a week will do no harm, quite the opposite. And, the more fish eat, the more the water quality deteriorates. This is why we all recommend leaving fish for a week or two weeks, some even three, when we go on vacation, rather than risk trouble. I was in hospital a couple times last year, and I lost none of my fish when they went two and three weeks without feeding.
 
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Seb2502

Seb2502

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Seachem's Flourish Comprehensive Supplement and their Flourish Tabs are high quality, I have had success for over a decade. In the UK, TNC Lite is much the same. There are undoubtedly others, but these are readily available for most members on TFF.

If your water is very soft (GH close to zero as mine is) there may be a need for additional calcium and magnesium, as these are minimal in the comprehensives since many have sufficient in the source water. I experimented for several years over this, and there are remedies.
I have root tabs that I use under my Amazon sword and crypts and it’s worked wonders.
I think I’ll look into getting a complete fertilizer because my rotala isn’t looking the greatest if you check my other post.

And yes my water is very soft
 

Byron

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And yes my water is very soft

This leads to another issue...the effect of these on fish. One reason never to use more than absolutely essential.

With very soft water, like yours and mine, if you have fish suited to such water the last thing you want to do is increase the GH. plants or no plants. The fish will unquestionably be better off (= healthier and less stress) in very soft water if that is how they evolved. When I came to this, I had one tank with fish that were more "middle of the road" in a sense, so I increased the GH to 5 dH (from 0). But in my other tanks with more sensitive wild caught fish I used plants that were happy without this. For me, fish were the primary focus, and plants were secondary.
 

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