Goldfish Slimecoats are Poison!

[Undawada]

This is a branch-off thread to keep this one on topic.

I (like a lot of aquarists) have heard that goldfish slime coats are poisonous to tropical fish. Bloozoo2 raised a good point in true skeptic fashion, that she could find no evidence that this was true, and wanted to research it. This also raised my curiousity.

Let's discuss scientifically. I'll start it off:

If goldfish slimecoats are poisonous, why do they use goldfish as feeders for tropicals? Wouldn't this indicate that this could be a myth started to encourage people to keep tropicals and cold water fish separate?

 

[WILDER]

Never heard of goldfish slime coats being poisonous to tropical fish, i have 3 female platys with mine, and they are thriving, as they got really big and they have never had fry, longest i have had platys, had them a year.

 

[black angel]

i've heard this as well and dont believe it. i have kept both together successfully in the past.

 

[Bloo]

My question is merely about the statement that their slimecoats are said to be poisonous / toxic to tropical fish. I am not in any way arguing about whether or not to keep goldfish and tropicals together and I do not believe that this is what this discussion should be about either.
I myself have just not been able to find documented evidence, to substantiate that statement is true.

 

[Undawada]

I agree. At least that I haven't seen evidence either.

My comment was to speculate that maybe the myth started as a simple way to keep newbies from keeping cold and warm water fish together, rather than explaining all the intricicies of fishkeeping and cold blooded metabolism... not to start a rant on tropical / coldwater compatibility )

Does anyone have any evidence either way? I don't want to argue, just curious now

 

[dwarfgourami]

As I meant to mention in the other thread (though I don't think it came out right), it doesn't seem to be in any of the commonly available books, though they all mention temperature incompatibility.

 

[MegTheFish]

Maybe the goldfish's slimcoat is only poisonous if the tropical fish ingests it? Like say the goldfish is dead and they start picking at it?

 

[WILDER]

Maybe the goldfish's slimcoat is only poisonous if the tropical fish ingests it? Like say the goldfish is dead and they start picking at it?

Good point made meg.

 

[AAJ]

OK folks

Regarding the Goldfish and Danios read on:

http/www.aquahobby.com/gallery/e_goldf.php

"Tankmates: Typically goldfish do best in a species only tank. Although it is quite possible to keep other fish with them. But you must be careful in the fish that you choose. They must be placid enough, have similar water requirements and be able to handle the lower temps (18-25°C) enjoyed by goldfish. I have had mounds of success with Zebra Danios, they are relatively close relatives, and do have a lot of the same requirements as goldfish. Apple snails are marvelous algae eaters for the goldfish tank. White Clouds would probably do OK in a gold tank as well. I wouldn’t put any of the more strictly "tropical" fish like tetras, and definitely not any cichlids. "

Looks as though some other fishkeepers have tried it with much success. I think the Slime thing is one of those myths.

They get along quite nicely in my tank and if it weren't for the ammonia issue I would keep them together.

 

[The-Raven]

they're not poisonous, end of story.

the reason you don't keep tropicals with coldwaters is because temperature (which goldfish are highly adaptive to anyway) and because coldwaters are exponentially messier, and generally grow larger and faster. poisonous? not even close.

 

[sinistral]

Here is an interesting article from Bob Fenner's website. Some fish do secrete a toxic body slime, but I haven't seen any evidence (like everybody else who posted) that goldfish do anything similar.

I wonder if this (mis)information was perpetuated by what you often read on the net about pleco's attacking goldfish for their body slime.

 

[MAM]

I also have to wonder if this is just a hold over from the early days of fish keeping. Someone wrote a book or an article stating a theory or a supposed fact. Someone else came along years later wanting to write another article or book. With few sources, they just copied what they found. And the cycle continued. There are a number of "facts" out there that came about this way and are slowly being disproven. Trouble is, the old sources are still around and still being used to write the new ones.

Just a thought...................

 

[Inchworm]

It's been a custom to keep cory cats, especially C.aeneus and C. paleatus, with goldfish and they never seemed to have a problem concerning the slime coats or any other thing. Of course, these corys can stand cooler temperatures than many of the others.

 

[Jules H-T]

I don't believe it for a second. I've kept mixed tropical and more than one goldfish together in the past. Considering that due to central heating in the house the tank was getting up to 26 degrees a lot of the time anyway, I decided that the heat was unlikely to be much more of an issue than it already was.

To address the possible ingestion factor, sadly I've seen one goldfish picked to the bones overnight, and none of the tropical tankmates showed any signs of ill health.

Perhaps it's also worth mentioning that a plec was in there and he certainly never tried to suck onto a goldfish!

The only real problem I came across was that as the goldies grew (which can happen pretty quickly in a well fed tank with high water flow) they overnight developed a taste for neons and wiped out 16 in a matter of hours.

Size, and the propensity for goldfish to eat anything smaller than their mouths, is the issue here AFAICS. A small goldfish is a sleeping giant, and on balance I would certainly advise against mixing them with smaller tropicals.