In theory...

[Rocky998]

So I was thinking, and I'm most likely wrong , that all fish are relatively easy to keep when you have the knowledge. Even someone like me, who doesn't know much but knows enough can most likely easily keep a discus when you have the right knowledge (and maybe after keeping a tank or two). And as long as you've got some extra cash to spend, the larger fish are actually easy as well (again, in theory). After some research I learned that discus are hard to keep because of their strict water parameters, but arent all fish that way? Of course there are some fish that can do 5-8 ph or 65-80°F but they all have some sort of thing you need to follow and sometimes a "harder to keep fish" can be easy due to the type of water you may have on hand.

(Again this is me just thinking aloud. I am not recommending that beginners go to the store now and pick up a discus but I am saying that in theory all fish have the "same" basic needs. So please dont think I'm trying to spread bad ideas on fish keeping.) I'm going to get criticized so bad lol.

 

[Bruce Leyland-Jones]

Once Upon A Time, discus (as an example) were only looked after successfully by really skilled aquarists. The fish were nearly always wild-caught and replicating their required water was a bit of a challenge.
Today, discus are bred all over the world and here in the UK, we have good access to east European discus. These fish have not been bred in water akin to their homeland and thrive in very different water. As a consequence, discus are more common and they are not quite as in need of specialised care as they once were.

That said, some fish will still only thrive in very specific and precise water conditions, whilst others will actually thrive in a wider range of waters. This doesn't just depend on where they've been bred, either.

Notice I used the word 'thrive', as opposed to 'survive' or 'just cope with'.
Many fish 'can just cope with' a wide variety of conditions that they might find themselves in. As a consequence, fish are kept in less-than ideal waters and their keepers spread the word how easy Fish A is to keep and that they have no problem keeping Fish B with a bunch of Fish C, or that their Fish D doesn't need a lot of friends, because they do very well with just me for company, etc.. This tends to blur the description of the better conditions for fish and this is complicated by many people having different definitions of 'thrive'.

I'll happily agree with you that "all fish are relatively easy to keep when you have the knowledge...(as long as you studiously apply that knowledge and "as long as you've got some extra cash to spend" and the time to provide the proper care.

 

[AbbeysDad]

You're basically correct - it's not rocket science. Once you understand some basics, it's fairly simple, just as it is for taking care of any pets. But as simple as it is, it requires due diligence to ensure a high water quality and proper feeding. And your right as well, that some species require special care, and larger fish need larger accommodations.
The pitfall is there are too many wannabe gurus that might convince you that you don't need water changes or swear by the one inch per gallon rule - so you have to take all the 'advice' (myths) out there with a good grain of salt.

 

[Byron]

Of course there are some fish that can do 5-8 ph or 65-80°F but they all have some sort of thing you need to follow and sometimes a "harder to keep fish" can be easy due to the type of water you may have on hand.

This is basically misunderstood by most, even some "experienced" fishkeepers. It is also a complex issue, and would take almost a book to fully delve into, so I will attempt the briefest summary.

Each species of freshwater fish has evolved to function in a very specific environment (water parameters, habitat conditions, numbers of the species, other species, etc). Some fish species are rigid in their need for this environment, while other species have the ability to function well in varying conditions. But one thing must be understood--this is not an ability to manage in changing conditions in a given aquarium. A species, for example the tetra Pristella maxillaris:

Water parameters: Very adaptable for a tetra. Soft to slightly hard (hardness 0 up to 30/35 dGH), acidic to basic (pH 5 up to 8.0) water, temperature 24-28C/74-82F. In hard water it will not be colourful.​

There is a biological reason for this tolerance, and it has to do with the habitats of this species. They occur in different areas that have wide divergence, from very soft/acidic to moderately hard/basic. But this does not mean that an individual fish of the species can adapt to varying conditions, because it cannot. What it does mean is that the species will be fine in very soft/acidic water, and it will be generally fine in moderately hard/basic water, but only if the water in either case remains the same. But as the citation above notes, there is a cost to harder water (for this species, but this actually applies to most soft water fishes).

So, to answer your question aren't all fish as difficult to keep as discus, I would say in a general sense, yes. One must know the requirements of a species respecting the environmental factors I mentioned above, and provide as close as possible. This is the only way to assume we are doing the best for the fish. Any deviance outside these parameters has consequences for the fish, as it affects the functioning of their metabolism, the processes that keep it alive by keeping the blood pH identical to the water around it (which is why fluctuating pH is so dangerous), keeping its tissues fed, its immune system working, etc. These processes are part of the genetic blueprint for each species, and they must be recognized.

A while back, a member posted a video of the species Hyphessobrycon eques (Serpae or Red Minor Tetra) in a habitat in northern Argentina (if memory serves me) where the water temperature was significantly cooler year round than it is in more northerly (for South America) regions where this species also occurs. The assumption was that the species could therefore be kept in almost any temperature range because of this, and fluctuating temperatures didn't matter. This is not at all the case. The species has evolved to function in cooler water in the geographical area in northern Argentina, but individuals of those fish cannot be plunked into the warmer water of the species populations that occur in say the basins of the Guapore and Paraguay rivers, or that of the upper Amazon, where the water temperature is much warmer. The species in these areas has evolved differently. And as an aside, it is no surprise really that Stanley Weitzman hypothesized that the wide geographical distribution of this species in differing waters likely involved different species. Phylogenetic analysis of a large number of fish collected from each region would determine whether Dr. Weitzman was correct, but given his authoritative status I would not doubt it.

As I have been typing, other members have posted, and one of tyhem makes a very significant point...survive and thrive are not the same thing. Read the citations in my signature block; these are absolute truths we must recognize and accept.

 

[Rocky998]

This is basically misunderstood by most, even some "experienced" fishkeepers. It is also a complex issue, and would take almost a book to fully delve into, so I will attempt the briefest summary.

Each species of freshwater fish has evolved to function in a very specific environment (water parameters, habitat conditions, numbers of the species, other species, etc). Some fish species are rigid in their need for this environment, while other species have the ability to function well in varying conditions. But one thing must be understood--this is not an ability to manage in changing conditions in a given aquarium. A species, for example the tetra Pristella maxillaris:

Water parameters: Very adaptable for a tetra. Soft to slightly hard (hardness 0 up to 30/35 dGH), acidic to basic (pH 5 up to 8.0) water, temperature 24-28C/74-82F. In hard water it will not be colourful.​

There is a biological reason for this tolerance, and it has to do with the habitats of this species. They occur in different areas that have wide divergence, from very soft/acidic to moderately hard/basic. But this does not mean that an individual fish of the species can adapt to varying conditions, because it cannot. What it does mean is that the species will be fine in very soft/acidic water, and it will be generally fine in moderately hard/basic water, but only if the water in either case remains the same. But as the citation above notes, there is a cost to harder water (for this species, but this actually applies to most soft water fishes).

So, to answer your question aren't all fish as difficult to keep as discus, I would say in a general sense, yes. One must know the requirements of a species respecting the environmental factors I mentioned above, and provide as close as possible. This is the only way to assume we are doing the best for the fish. Any deviance outside these parameters has consequences for the fish, as it affects the functioning of their metabolism, the processes that keep it alive by keeping the blood pH identical to the water around it (which is why fluctuating pH is so dangerous), keeping its tissues fed, its immune system working, etc. These processes are part of the genetic blueprint for each species, and they must be recognized.

A while back, a member posted a video of the species Hyphessobrycon eques (Serpae or Red Minor Tetra) in a habitat in northern Argentina (if memory serves me) where the water temperature was significantly cooler year round than it is in more northerly (for South America) regions where this species also occurs. The assumption was that the species could therefore be kept in almost any temperature range because of this, and fluctuating temperatures didn't matter. This is not at all the case. The species has evolved to function in cooler water in the geographical area in northern Argentina, but individuals of those fish cannot be plunked into the warmer water of the species populations that occur in say the basins of the Guapore and Paraguay rivers, or that of the upper Amazon, where the water temperature is much warmer. The species in these areas has evolved differently. And as an aside, it is no surprise really that Stanley Weitzman hypothesized that the wide geographical distribution of this species in differing waters likely involved different species. Phylogenetic analysis of a large number of fish collected from each region would determine whether Dr. Weitzman was correct, but given his authoritative status I would not doubt it.

As I have been typing, other members have posted, and one of tyhem makes a very significant point...survive and thrive are not the same thing. Read the citations in my signature block; these are absolute truths we must recognize and accept.

Yes, when I talked about some specimens being able to thrive in different conditions, I wasnt meaning continuously changing parameters.

 

[AbbeysDad]

This is basically misunderstood by most, even some "experienced" fishkeepers. ..........

Whew .... What he said.