37 gl tank, how many fish I can put in!!!! 9 fishes now but the tank looks empty!!!

I agree with the advice from @Essjay that you need to ascertain the GH of your tap water. Terms like "soft" are subjective without knowing the actual number. Check your water authority's website, the data may be there. GH is the most important, but it would be useful to know the KH (Alkalinity, or carbonate hardness) and their pH number.

Second, I also agree the Silver Dollars should be re-homed. They can get rather aggressive without a larger group, they will still not be all that "friendly" with many other fish, and they eat plants (if you intend live plants...and floating plants are always beneficial with most forest fish). Leaving the three for a year could be even more trouble, as this is contrary to their expectations of living in larger groups, and that means detrimental effects on the fish. It is sad that so many fish store staff do not have the knowledge to properly caution customers on these issues, as it is the fish that suffer the consequences, and none of us want that.

If you intend cory catfish, you should have a sand substrate to provide what they need.
 

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I agree with the advice from @Essjay that you need to ascertain the GH of your tap water. Terms like "soft" are subjective without knowing the actual number. Check your water authority's website, the data may be there. GH is the most important, but it would be useful to know the KH (Alkalinity, or carbonate hardness) and their pH number.

Second, I also agree the Silver Dollars should be re-homed. They can get rather aggressive without a larger group, they will still not be all that "friendly" with many other fish, and they eat plants (if you intend live plants...and floating plants are always beneficial with most forest fish). Leaving the three for a year could be even more trouble, as this is contrary to their expectations of living in larger groups, and that means detrimental effects on the fish. It is sad that so many fish store staff do not have the knowledge to properly caution customers on these issues, as it is the fish that suffer the consequences, and none of us want that.

If you intend cory catfish, you should have a sand substrate to provide what they need.
They mentioned GH of 30 in Ottawa tap water. Same for KH it is around 30ppm for caCO3
 
20 days? What does the ammomia and nitrites read? If you have answered this before, sorry for asking
 
They mentioned GH of 30 in Ottawa tap water. Same for KH it is around 30ppm for caCO3

OK, that is very soft water (another subjective term!!). GH of 30 ppm equates to 1.6 dH, these two units (ppm and dH) are the ones common in the hobby. You will be fine with almost any fish species native to South America and SE Asia. Avoid all hard-water requiring species like the livebearers, rift lake cichlids, and some rainbowfishes (not all, but some), and a few others here and there. But you have a huge selection of options from the characins (tetras, hatchetfishes, pencilfishes), cyprinids (rasboras, danios, barbs, loaches), most catfishes, gourami, etc. From the perspective of the water that is, obviously not all of these will work together for various reasons.

These numbers also mean that over time as the aquarium becomes biologically stable, the pH is likely to lower, which is fine. Soft water fish generally like acidic water, but the pH is OK as is, don't mess with trying to adjust it.
 
20 days? What does the ammomia and nitrites read? If you have answered this before, sorry for asking
Yesterday the ammonia was between 0.5 and 1 ppm so I made a water change. There was also some level of nitrite and nitrate. I will keep testing and doing water changes until it is stable.
 
Yesterday the ammonia was between 0.5 and 1 ppm so I made a water change. There was also some level of nitrite and nitrate. I will keep testing and doing water changes until it is stable.
Make sure they are large water changes. What does your water company use in their water? If it is just chorine the regular water conditioner will work, but if its choromines then you need a different type of conditioner
 
OK, that is very soft water (another subjective term!!). GH of 30 ppm equates to 1.6 dH, these two units (ppm and dH) are the ones common in the hobby. You will be fine with almost any fish species native to South America and SE Asia. Avoid all hard-water requiring species like the livebearers, rift lake cichlids, and some rainbowfishes (not all, but some), and a few others here and there. But you have a huge selection of options from the characins (tetras, hatchetfishes, pencilfishes), cyprinids (rasboras, danios, barbs, loaches), most catfishes, gourami, etc. From the perspective of the water that is, obviously not all of these will work together for various reasons.

These numbers also mean that over time as the aquarium becomes biologically stable, the pH is likely to lower, which is fine. Soft water fish generally like acidic water, but the pH is OK as is, don't mess with trying to adjust it.
Yes the Ph dropped last days under 6.5 so at Petsmart they urged me to do a water change. When I read in the forums, I understood that the low KH is the cause of having ph drops because there is not carbonates to buffer. So what I did is to buy crushed coral and few to the gravel. I hope this is fine!
 
Make sure they are large water changes. What does your water company use in their water? If it is just chorine the regular water conditioner will work, but if its choromines then you need a different type of conditioner
Well, I really don't have an idea :oops::oops: Please find attached the quality report for our tap water. Let me know your opinion. I am using API stress coat.
 

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OK, that is very soft water (another subjective term!!). GH of 30 ppm equates to 1.6 dH, these two units (ppm and dH) are the ones common in the hobby. You will be fine with almost any fish species native to South America and SE Asia. Avoid all hard-water requiring species like the livebearers, rift lake cichlids, and some rainbowfishes (not all, but some), and a few others here and there. But you have a huge selection of options from the characins (tetras, hatchetfishes, pencilfishes), cyprinids (rasboras, danios, barbs, loaches), most catfishes, gourami, etc. From the perspective of the water that is, obviously not all of these will work together for various reasons.

These numbers also mean that over time as the aquarium becomes biologically stable, the pH is likely to lower, which is fine. Soft water fish generally like acidic water, but the pH is OK as is, don't mess with trying to adjust it.
Here is the quality report of our tap water.
 

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Yes the Ph dropped last days under 6.5 so at Petsmart they urged me to do a water change. When I read in the forums, I understood that the low KH is the cause of having ph drops because there is not carbonates to buffer. So what I did is to buy crushed coral and few to the gravel. I hope this is fine!

I would not do this, and I would remove the crushed coral. There is a considerable level of misunderstanding in this hobby about water parameters, and making this even worse is the fact that most fish store staff do not have an inkling of what is involved, so the myths continue to be spread. I'll try to explain this as briefly as I can.

The source water will have specific parameters, namely GH, KH and pH. The GH and KH impact the pH, with respect to possible fluctuations over time. With very soft water (low GH as here), and a corresponding low KH which is what "buffers" the pH, the pH is more at liberty to fluctuate. As I mentioned previously, the pH will tend to become acidic because of the normal biological processes. This is where the water parameter requirements of fish come into the equation.

Freshwater fish have evolved over thousands of years; each species has evolved to function best in the environment in which it has evolved, and with freshwater these are very different. Water is a powerful solvent, which means it easily assimilates dissolved substances as it passes through or over them--minerals from rocks, organics, etc. A fish from very soft water, such as is found throughout most of South America, will be healthiest in similar water. By contrast, a fish from Mexico and Central America, such as mollies, have evolved in much harder water, and their physiology requires a lot more dissolved minerals in the water. Freshwater fish "drink" by taking in water via osmosis through their external cells; substances dissolved in that water that are able to diffuse across the cell membrane will also enter the fish, into the bloodstream and be carried to internal organs. Minerals like calcium especially in the water thus get inside the fish; in soft water species this causes serious trouble as it will in time block the kidneys and the fish dies, but in hard water species they use that calcium because their physiology has evolved accordingly.

So fish from soft water are at their best in similarly soft water, and usually this means an acidic pH, below 7. If you were to keep livebearers, you would need to increase the GH (calcium and magnesium are the primary minerals here), and the pH would naturally be higher, on the basic side, above 7. There is no point in adding calcium via crushed coral or anything else if you keep soft water species in soft water.
 
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I would not do this, and I would remove the crushed coral. There is a considerable level of misunderstanding in this hobby about water parameters, and making this even worse is the fact that most fish store staff do not have an inkling of what is involved, so the myths continue to be spread. I'll try to explain this as briefly as I can.

The source water will have specific parameters, namely GH, KH and pH. The GH and KH impact the pH, with respect to possible fluctuations over time. With very soft water (low GH as here), and a corresponding low KH which is what "buffers" the pH, the pH is more at liberty to fluctuate. As I mentioned previously, the pH will tend to become acidic because of the normal biological processes. This is where the water parameter requirements of fish come into the equation.

Freshwater fish have evolved over thousands of years; each species has evolved to function best in the environment in which it has evolved, and with freshwater these are very different. Water is a powerful solvent, which means it easily assimilates dissolved substances as it passes through or over them--minerals from tocks, organics, etc. A fish from very soft water, such as is found throughout most of South America, will be healthiest in similar water. By contrast, a fish from Mexico and Central America, such as mollies, have evolved in much harder water, and their physiology requires a lot more dissolved minerals in the water. Freshwater fish "drink" by taking in water via osmosis through their external cells; substances dissolved in that water that are able to diffuse across the cell membrane will also enter the fish, into the bloodstream and be carried to internal organs. Minerals like calcium especially in the water thus get inside the fish; in soft water species this causes serious trouble as it will in time block the kidneys and the fish dies, but in hard water species they use that calcium because their physiology has evolved accordingly.

So fish from soft water are at their best in similarly soft water, and usually this means an acidic pH, below 7. If you were to keep livebearers, you would need to increase the GH (calcium and magnesium are the primary minerals here), and the pH would naturally be higher, on the basic side, above 7. There is no point in adding calcium via crushed coral or anything else if you keep soft water species in soft water.
This is very interesting and clarifying! If I correctly grasped the idea here, my soft water (if not altered) is better suited for soft water fish from south america and south asia (tetras, gouramis, etc) while hard water species such as livebearers need harder water. This totally make sense to me now and gave me an idea of adding a second aquarium that will be dedicated to hard water species (of course adding crushed coral to make the water hard for these guys). A third aquarium will be for saltwater fish like clown fish! I am very excited about this ''science'' :)
 
With a pH well below 7, the ammonia reading will all be in the ammonium form so it won't harm the fish. Had the pH been over 7, it would be a different story.*

But there is no safe form of nitrite, and whenever there is a reading above zero you need to do a water change to get it back down to zero. This is why cycling with fish is hard work.



*Ammonia in water exists in 2 forms - ammonia, which is toxic to fish, and ammonium, which is a lot less toxic. The amount in each form depends on the pH. Above pH 7.0, there is a lot in the toxic form, but below pH 7, most if not all is in the less toxic form. Our test kits measure 'total ammonia' which is both forms combined so we can't tell from the ammonia test alone how harmful the water is. We need to look at pH as well.
 

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