Two types of fish. Acid and Alkaline

[itiwhetu]

There are two types of fish those that like acid tanks and those that like Alkaline tanks. On this site virtually every sick fish is a fish that is being kept in a tank that is outside of its comfort zone.
Cardinal Tetras will not be happy in pH 7.2
Bumble Gobies will not be happy in pH 6.8
Corydoras won't be happy in pH 8
Guppies won't be happy in pH 6.5
Please check the pH of your tank and match your fish to that pH. If your reference material says a fish will be happy pH 6-8, don't trust it find a reference that has a more accurate pH number.
If you are going to give your tank large water changes then you will struggle to have low pH as almost all water from the tap is Alkaline, this will then limit the fish you can keep.
If you do small water changes with a large amount of plant in your tank, then you will find acidic tanks are possible and the range of fish you can keep increases.
These are the decisions you need to make when keeping fish, please don't believe that any fish can live in a tank with a pH range 6-8. Somewhere along the line that fish will get stressed and sick and possibly die.

 

[Rocky998]

Dont worry! I always keep my PH somewhere inbetween 5 and 8! LOL

 

[threecharacters]

Nonsense, there are many fish that can span the range in pH. Consider Pseudomugil gertrudae, these have been collected in the wild in water conditions spanning Temp. 12 – 34° C pH: 3.68 – 9.4.

There are not "two types" of fish. This binarity is just flat out incorrect. That's why pH is measured on a spectrum not with two values.

 

[Uberhoust]

Nonsense, there are many fish that can span the range in pH. Consider Pseudomugil gertrudae, these have been collected in the wild in water conditions spanning Temp. 12 – 34° C pH: 3.68 – 9.4.

I will agree that are really not just two types of fish but in general there are, because in general there are two types of drainage systems, ones that have more precipitation and more organic materials in the water to drive down the pH, and reduce the hardness, and more arid or steeper drainage systems where evaporation and bedrock types tend to result in higher hardness and higher pH. Balance is very uncommon in nature and water chemistry is typically driven towards soft and low pH or hard and high pH.

If you match the fish you keep to the type of water you have then it is typically easier to maintain the health of the aquarium. It is a general rule, and a good one if you are just starting out.

 

[threecharacters]

I will agree that are really not just two types of fish but in general there are, because in general there are two types of drainage systems, ones that have more precipitation and more organic materials in the water to drive down the pH, and reduce the hardness, and more arid or steeper drainage systems where evaporation and bedrock types tend to result in higher hardness and higher pH. Balance is very uncommon in nature and water chemistry is typically driven towards soft and low pH or hard and high pH.

If you match the fish you keep to the type of water you have then it is typically easier to maintain the health of the aquarium. It is a general rule, and a good one if you are just starting out.

I agree about matching fish to your water. My point is that a lot of water condition information available online for aquarium fish is anecdotal and incomplete. Bumblebee Gobies are a great example of this. Previously they were thought to be brackish only. However, as collection information improved it became obvious that they also live in soft freshwater. Still the overwhelming recommendation online is that they're exclusively brackish fish. If we acknowledge that this information is often incomplete we're more likely to accept new information when it becomes available.

That's a good point about different water drainages in general leaning towards one type of water. However, there will always be micro-climates within each drainage. The pH in a main channel may be very different than the pH in a nearby oxbow and the same fish species may be happy in both. pH will also change with the seasons in the same drainage. I think there is a general failure to recognize the variety of water conditions that many (not all) freshwater fish can live in. I think some really notable exceptions to this are fish that live in water with very static water conditions e.g. marine fish and rift lake cichlids.

 

[Caesar]

My tap water is 6.5 with a TDS of 7, benefits of living in a rain forest

As mentioned by threecharacters, unless a fish lives in a vast body of water, it's going to experience shifts in pH, temperature, etc with weather, seasons, etc. It's a feature of freshwater fish to be adaptable. During streamkeeping I've observed the creek span pH from 7.2-8.8, temperature range from 2°C to 27°C, conductivity range from 114µs/cm to 508µs/cm, etc.

 

[Byron]

There is more to this than what has so far been mentioned. First thing to understand is that for most fish it is not the pH that is a priority but the GH which as most of us know (I hope) is the level of dissolved mineral, calcium and magnesium primarily, in the water. This directly impacts the day to day functioning of the fish's physiology. There are fish that will only function well in soft water, fish that only function in hardish water, and fish that have some degree of managing in the middle, to either side. And "functioning well" for soft water species and hard water species sometimes means exclusively, i.e., they will only live in such water.

The pH generally tends to match the GH, being higher (basic) in harder water or lower (acidic) in softer water. So getting the GH right, which must be the goal, will usually bring the pH in line for the species. There are always exceptions of course, but they are few among the thousands of species.

The fish that manage well "in the middle" means in a pH in the 6's or 7's and with a moderately soft/hard GH, and there are many such species.

There are also species like the gobies mentioned previously that have a significantly wider range, to the point of being somewhat extreme at first glance. There is, so far as I have discovered, always a good reason for the latter--the species has evolved in geographically separated habitats that have these widely divergent parameters. This does not mean that individual fish of the species can switch from one extreme to the other--usually they cannot--but it means that the species has the difference depending upon the source. Sometimes the fish can do quite well in either set of parameters, provided it is stable; Pristella maxillaris comes to mind.

To the pH itself, fish do have a wider tolerance here than they do for GH, again generally speaking. The GH of their source habitat rarely if ever varies because it is determined by permanent factors (organics, minerals, etc). The pH is to a degree variable in some situations, but this has limits. The diurnal fluctuation in pH that occurs in nature (and in especially planted aquaria) involves a few decimal points in pH. Fish tolerate this with no problems. The often-mentioned seasonal pH shift is not as significant as some seem to think, and when it does occur it is certainly not rapid. Fish require weeks and sometimes months to adjust to significant shifts in parameters; this is why most do not bother with "drip acclimation," it just does nothing beneficial.

This does not deal with the so-called ability of very soft water fish to live in moderately hard water, and the reverse.

 

[itiwhetu]

The purpose of this thread was to try to get some of the newcomers away from keeping fish in what would be described as not ideal conditions. But everyone has done a good job of justifying why they can keep their fish in a tank with any pH.
I just wish these members will then comment and fix the numerous problems associated with pH on this forum site.

 

[kribensis12]

I think the moral of this story is: Do research and make sure that the fish you are keeping are suited to your tanks habitat. It's one of the most basic levels of fishkeeping but due to it's "inconvenience" and the desire to make a living, it's rarely accurately explained at any LFS.