Common Freshwater Fish to Avoid in Home Aquaria

Delhezi222

Fire Eel
MFK Member
Oct 21, 2007
2,190
8
68
P
Hey all. I thought I'd write an article about big and bad fish in home aquaria. Keep in mind this may not apply to many of us on monsterfishkeepers, but I still think it's important.
Here you go:

Many of you have encountered that one little fish in the fish store, the cute little fish that seems like it would be perfect in one of your tanks. Unfortunately, the real truth is that many of these fish will not stay small forever, and that they have requirements that many fishkeepers can not provide. Here I will give you a list of these fish, and the reasons why most fishkeepers do not have the adequate space and time needed to keep these fish.

The first fish is the commonly seen pacu. There are two species of pacu that are often seen in fish stores. The first is the red-bellied pacu. The red-bellied pacu, colossoma brachypomum, is the more common species of pacu. The other species is the black pacu, colossoma macropomum. The problem with pacu is that they are very commonly sold for a small price. They are attractive as juveniles, but they can grow up to be around two or three feet long, and also very heavy and thick. This is too large a size for many aquarists to handle. The other problem with pacu is that fish store employees often underestimate the size of pacus and advertise smaller sizes to prospective customers. Also, small pacu are often confused with piranha, which may cause some fish stores to mislabel them. In conclusion, a great alternative to pacus is silver dollars. They are much smaller than pacus, and they are a very nice schooling fish.

The next fish on the list is the red-tailed catfish, phractocephalus hemioliopterus. The big problem with these fish is their maximum sixe of up to four or five feet long. They are often sold in fish stores as cute little juveniles, but they have a voracious appetite and will quickly grow in size. Another problem that many people don't realize is that you can't just buy the fish when it's small and then sell it once it get's big. The problem with that is that you will often not be able to find someone to buy such a large fish. Ultimately, size is one of the only problems with this fish. They are good eaters, and are very peaceful fish, but most people should not keep them.

The next fishes are the arowanas. They are a very nice fish, and many people successfully keep them. However, the problem with arowanas are that they can become very large. The silver and closely related black can get up to around three or four feet long, and the jardini arowana can sometimes get up to around three. There are very little problems with the silver or black arowana aside from size, and if you have a two-hundred and forty gallon fish tank or larger, I highly recommend them. The only problem with the jardini is that it is often extremely aggressive. However, if kept alone, it is a very nice fish, and looks really good. The leichardti arowana is very similar to the jardini, and has most of the same requirements. The last arowana is the asian arowana, which is illegal in the united states. However, if you are outside of the united states, they are a beautiful fish, but they can become expensive. The only reason to avoid the arowana species is because of the maximum size, but if you have a large enough tank they are great fish.

Another fish that is commonly sold in fish stores is the clown knifefish. This species of knifefish can grow to at least three feet long, and possibly even larger. However, buying these fish is similar to the situation with arowanas. They are a very nice fish aside from their maximum size. They are very attractive as juveniles, and are usually not very expensive.They can be slightly aggressive as they grow larger, but they are still a very nice fish. They can be kept in large tanks, and I would recommend them to anyone with large enough tanks. They can be slightly aggressive as they grow larger, but they are still a very nice fish.

The next fish is an extremely large fish, the alligator gar. They are sometimes sold as other species of gar, so sometimes people are surprised when the bought a gar that was supposed to stay much smaller than an alligator gar, and the fish turns out to be an alligator gar. There are a few problems with alligator gar. First is the obvious reason of size. They can grow to be up to eight to ten feet long, and they can be pretty thick. Another problem is that they can be aggressive, and not many fish can hold their own against a ten foot long fish with rows of sharp teeth. Ultimately, no one without an extremely large tank should keep them.

A larger relative of many smaller fish is the next fish. This fish is the giant gourami. It grows to a length of up to two feet. This is not to large of a fish, and can be kept in tanks fairly easily. The problem, however, is that most people aren't expecting the cute little four inch fish at the fish store to grow up to be such a large fish. As a result, many people don't have tanks large enough for the fish when they buy it. However, if you do have sufficient tank space available, they are a highly recommendable fish with a lot of personality.

Another fish to be wary of is the oscar, a fish which is very common in fish stores everywhere. The oscar is a well-known aquarium fish. It grows to a maximum length of over a foot, and although this is not an enormous maximum length, they are often bought by people with far too small tanks. Another concern with oscars is that they are very voracious eaters. This causes two problems. First, they will eat many small fish if they are kept with them, although they are not aggressive. Second, as with any fish that eats a lot, they give of a lot of waste, which means frequent water changes may be needed if they are in a tank smaller than advised. However, if you have a tank large enough for an oscar, they are a very nice fish, which many people keep.

Another catfish on the list is the channel catfish. They are a north american fish that can grow very large in a short amount of time. They can grow to be over three feet long. Also, as with all catfish they are very voracious eaters. They are often sold as little juveniles, and albinos are commonly available. Many people buy them expecting them to stay small, but sadly they do not. However, they are a very peaceful and personable fish, and they can be kept successfully in aquaria.

One of the more unusual catfish on the list is the common pleco, hypostomus plecostomus. Often referred to as "suckerfish" by less than knowledgeable fish store employees, there are a few things wrong with the common pleco. One problem is the size. Common plecos are often advertised as being small fish, but they can actually grow to about two feet long. Also, they are often advertised as being excellent algae-eaters, but they actually give off more waste than they get rid of. However, plecos are still very nice fish, and many fishkeepers have kept them at some point.

Yet another large catfish that some fishkeepers run into commonly is the tiger shovelnose catfish. Often sold at fish stores as small, cute little catfish, they can grow to a maximum size of up to around three or four feet. As with every other catfish mentioned, they eat a lot of food. Many people aren't prepared for such a demanding fish, although if you do have enough tank space and time for them, they can become a very interesting and beautiful fish.

As you can see, there are many catfish on the list. Another catfish to add is the shark catfish, a fish that is often sold as many different names. One of those is the silver-tipped shark. The main reason the shark catfish is problematic is not because of it's size, although it can grow to be over a foot long, maybe even two feet. The problem is that it is a brackish fish, which means that it needs some amount of salt in it's water. Many fish store employees neglect to tell buyers that, and as a result many people often stick them in inappropriate situations. However, if you do have an adequate brackish tank set up, they are a very nice fish.

A large barb on the list is the tinfoil barb. The main reason the tinfoil barb is a problem is simply because of it's maximum size. Although most people think that it will stay small, it will actually grow to a size of over one foot long. This may not seem yo large of a maximum size, but when you combine that with the massive amount of waste fish like these give off, you get a pretty dirt tank, which means frequent water changes may be needed if the fish is in a small tank. If it's in a large tank, however, it can be a very nice schooling fish.

Perhaps the most common of all these fish is the well-known goldfish. Almost every fish store has them at all times. The main problem with goldfish is actually the lack of knowledge of many fishkeepers. Many people try to keep goldfish in bowls or extremely small tanks. However, goldfish can actually grow up to a foot long. Also, they give off a large amount of waste, which often makes tank cleaning more difficult. However, goldfish are a relatively hardy and peaceful fish which are great beginning fish to be kept by people with adequately sized tanks.

The final group of fish is the freshwater stingray group. The freshwater stingrays are a very beautiful and interesting group of fish, however they are not for everybody. They are not too common in fish stores, but they do pop up every once in a while. There are a few problems with keeping freshwater stingrays. One is that most grow to a large size, and they need large tanks. Another problem is that some freshwater rays are known to be very picky eaters. Most people are not able to give them all the things they need to be healthy and happy. However, if you do a sufficient amount of research and acquire all you need to house them, they are a very unique group of fish.

In conclusion, there are many groups of fish that are not always advisable for home aquaria. Learning about these fish and researching all that you can is the best way to become a better fishkeeper, and with enough work maybe you will one day be able to keep many of these hard-to-keep fish.
Thank you for reading, and I hope I helped you in some way.
 

1974Pantera

Feeder Fish
MFK Member
Aug 3, 2008
734
0
0
San Carlos, Ca.
Good post! The only caveat is that I have never owned a Jardini that was overly aggressive. I will mention that I never fed them live food and kept them with other fish and never had a problem.
 

Delhezi222

Fire Eel
MFK Member
Oct 21, 2007
2,190
8
68
P
1974Pantera;2374699; said:
Good post! The only caveat is that I have never owned a Jardini that was overly aggressive. I will mention that I never fed them live food and kept them with other fish and never had a problem.
Really?
That's very interesting. I'll bet the people in the aro forum would love to hear about that.
 

Malawi-

Jack Dempsey
MFK Member
Oct 20, 2008
1,211
2
38
Oregon
Good info. ;)
 

cornbread_5

Fire Eel
MFK Member
Apr 29, 2007
1,586
9
68
42
connecticut
the only that i would add is oscars even though they do not get three feet , people by them and besides pacu i think its the most returned fish due to its size , cuz people think they can keep it in a 10 gal or something crazy like that
 

Delhezi222

Fire Eel
MFK Member
Oct 21, 2007
2,190
8
68
P
cornbread_5;2374747; said:
the only that i would add is oscars even though they do not get three feet , people by them and besides pacu i think its the most returned fish due to its size , cuz people think they can keep it in a 10 gal or something crazy like that
Yeah, I considered adding an oscar. If I ever get around to it, I'll try to.

On another note, this is my 1000th post!:headbang2
 

sizors

Gambusia
MFK Member
Jul 30, 2008
245
0
16
Orlando / Casselberry FL
cornbread_5;2374747; said:
the only that i would add is oscars even though they do not get three feet , people by them and besides pacu i think its the most returned fish due to its size , cuz people think they can keep it in a 10 gal or something crazy like that
I too would suggest putting something in there about oscars.
I dont necessarily think that you need the part about stingrays though, because as you said, they are really not that common.
 

abortedsoul

Feeder Fish
MFK Member
Sep 4, 2008
1,154
1
0
MD, USA
This was a really useful post... I am glad that you put it up here, and I think more people should read it! I had an alligator gar in my turtle tank when I was younger, and wow did that thing get big.

All-in-all good advice... thx for posting!
 

Delhezi222

Fire Eel
MFK Member
Oct 21, 2007
2,190
8
68
P
sizors;2374763; said:
I too would suggest putting something in there about oscars.
I dont necessarily think that you need the part about stingrays though, because as you said, they are really not that common.
Yeah, I wasn't originally going to put the part about the rays, but I thought it would be helpful. I'll add the part about oscars.

abortedsoul;2374764; said:
This was a really useful post... I am glad that you put it up here, and I think more people should read it! I had an alligator gar in my turtle tank when I was younger, and wow did that thing get big.

All-in-all good advice... thx for posting!
No problem. Thanks for reading.
 
zoomed.com
hikariusa.com
aqaimports.com
Store