Are spiny eels actual eels?

[Laticauda]

True eels are still a type of fish. Spiny eels are not true eels, it has to do with gill and other body structure variants.

 

[jclyde13]

Eels in the genus Anguilla have pectoral fins and some spend quite some time in freshwater.

They spend time in freshwater, but they are not freshwater fish. When you apply the term "freshwater" to a fish, that implies that it lives its entire life in freshwater, which is not true for true eels.

 

[jclyde13]

^^ +1 All true eels are either brackish or SW. I read somewhere that spinies are more closely related to loaches, but I never found out whether or not that was true (they do look somewhat similar, though).

I looked it up just now and found that it is actually not true (or at least if it is true, then it is to such a small extent that it really wouldn't make a difference).

 

[fishmamma]

I've just read that they are elongated fish.

 

[Laticauda]

They spend time in freshwater, but they are not freshwater fish. When you apply the term "freshwater" to a fish, that implies that it lives its entire life in freshwater, which is not true for true eels.

Well, from what I understand, anything that is not "full marine" is "freshwater." Seems stupid to us, but that's where the confusion comes from.

 

[jclyde13]

I've just read that they are elongated fish.

They are, but so are eels.

Well, from what I understand, anything that is not "full marine" is "freshwater." Seems stupid to us, but that's where the confusion comes from.

I'm not sure I understand what you mean... are you saying that bull sharks, Gymnothorax tile, figure 8 puffers, the various species of shark catfish, etc. are all freshwater fish?

 

[EmrePekdeniz]

They spend time in freshwater, but they are not freshwater fish.

Anguilla species are freshwater fish that migrate to the ocean to spawn. They are catadromous.

 

[jclyde13]

Anguilla species are freshwater fish that migrate to the ocean to spawn. They are catadromous.

Fish that regularly move between FW and SW usually do best in captivity in brackish water, so I would not consider them to be freshwater fish. And like I said before:

When you apply the term "freshwater" to a fish, that implies that it lives its entire life in freshwater, which is not true for true eels.

 

[EmrePekdeniz]

Fish that regularly move between FW and SW usually do best in captivity in brackish water, so I would not consider them to be freshwater fish.

Anguilla species can and do live in FW. They do not regularly move between FW and SW: they migrate once to the Sargasso Sea as adults, spawn, and die. (They can no longer eat once they start their migration.) The spawned eels migrate back to freshwater and complete their lifecycle there. So unless you want to keep a very young glass eel, which is unlikely, I don't think they would welcome brackish water.

Edit: American and European eels migrate to Sargasso Sea. Other eels have different migration locations. Too much salt in a captivity aquarium can even trigger the spawning mode and cause them to starve.

 

[Laticauda]

I'm not sure I understand what you mean... are you saying that bull sharks, Gymnothorax tile, figure 8 puffers, the various species of shark catfish, etc. are all freshwater fish?

Not bull sharks, since they "can" and "do" live in full marine (but so do G. tile) but I'm not the one who made up the "freshewater" terminology. I'm just stating the "reasoning" behind why so many people call G. tile, A. grunniens et al "freshwater" anything!