Why can't I keep goldfish with tropical fish?

[gsparsan]

I had a goldfish in a tropical fish tank for about 6 months before setting up a tank for it. The temperature didn't seem to be a problem. An unheated tank would be around 25°c here. The goldfish was doing great except for 2 things.

1. Many tropical fish are fin nippers and just can't resist the long flowing transparent fins of a nice goldfish.

2. I wanted my tropical tank to be a planted one. But my goldfish was a terrible gardener. We never agreed on the best positions of the plants!

 

[reptileguy2727]

Goldfish can actually live in temps even higher than almost any tropical fish can tolerate. Small ponds baking in the sun in southern Florida get hot. And yet the goldfish in them are loving it, even breeding. When the temps get that high it is not the temp that kills goldfish, it is the lack of oxygen. Keep the aeration up and there is not an issue. Fishbase.org (one of the best resources for ACTUAL max sizes, natural conditions, etc.) lists goldfish as going up to 100F. This would explain their ability to be fine in well-aerated small ponds in hot climates. Anyone saying they can't tolerate temps above 70F is improperly informed. They have no issues at all being in the upper 70s and even well into the 80s.

Diet is not as much of an issue as many make it out to be. I only feed New Life Spectrum to all my fish. The actual formula effectively does not vary from one variety to another. So my fish are all getting the same diet (and doing better on this high quality diet than any other diet I have ever tried).

Goldfish are not dirty. A high quality food that they use properly (as in it does not just come out the other end and offer little for them to actually use) cuts down on their waste a lot, just like with any fish. They do not produce any more waste per weight than a tropical fish. Bring cichlids into the conversation and the goldfish may be even cleaner.

Behavior is one of the biggest reasons. Long-bodied goldfish are aggressive eaters. Stick them in with some laid back tropicals and the tropicals could starve, but most tropicals would be fine. Plecos will suck on round-bodied goldfish doing severe damage, even in just one night. Many fish are too nippy and will peck at the slime coat of the goldfish, especially the slower round-bodied breeds.

In reality it is possible to safely mix goldfish and carefully selected tropical fish. In addition, there are a number of fish that naturally prefer cooler waters that do very well with goldfish: guppies, platies, mollies, swordtails, danios, white cloud mountain minnows (all actually not tropical but sub-tropical and prefer temps of about room temp just like the goldfish), dojo/weather loaches, and rosey reds. Some of these may be too fast and nippy to be in with the slow round-bodied breeds, but are still compatible with goldfish in general.

 

[piggy67]

This is all very good information,however it has been my experience that most fish species can adapt very well.This is also true for gold fish.I have kept gold fish in tropical tank's with several different fish species including angel's,tetras,guppies.Do they produce more amonia(yes,according to the above post's)but it's nothing weekly water changes can't handle.Can they handle higher temp's(no,according to the above post's)but mine have been doing fine for years,even thriving.I'm not knocking the above post's ,but imo and has been my experience that gold fish aswell as many other species can survive and thrive in conditions that are not optimal......

here they are..

 

[syddakyd]

goldfish can be kept with cool water fish such as friendly native fish, dojo loaches, white clouds(although may be eaten) etc

 

[Kashta]

It isn't a matter of adaptability. Goldfish don't have a stomach, so most of the proteins they ingest passes right through undigested into the water column, again. That's where the ammonia comes from.

 

[galen]

here they are..

a very nice fish tank. pretty goldfish too!

 

[reptileguy2727]

They do have a stomach. However, as an herbivorous omnivore it is small and adapted to taking in small quantities of food many times throughout the day, not just big occasional meals the way a piscivore would. They are capable of digesting protein, but it should not be a huge part of their diet. Again, a high quality diet made with easily digestible ingredients they can actually use is more of an issue than the protein level or the fact that they are a goldfish. The same goes for other fish too. Give tropical fish a low quality food with a bunch of fillers and most of it will come out the other end just to rot in the tank, resulting in a reduction in water quality and rise in the nitrate concentration.

 

[KarlTh]

It isn't a matter of adaptability. Goldfish don't have a stomach, so most of the proteins they ingest passes right through undigested into the water column, again. That's where the ammonia comes from.

If they had a larger stomach, the same amount of ammonia would be produced. The nitrogen would just spend a bit longer going through the fish.

Regardless of stomach size, messiness of eating or anything else, the equation is extremely simple:

N in (protein) - fish growth = N out (ammonia)

Generally fish growth is actually quite small compared with the protein added, so for practical purposes it's:

N in (protein) = N out (ammonia)

That's how fishless cycling by adding fish food to an empty tank works; it doesn't matter whether the nitrogen goes through a fish or not; it ends up as ammonia, and the amount depends on how much you put in.

 

[piggy67]

It isn't a matter of adaptability. Goldfish don't have a stomach, so most of the proteins they ingest passes right through undigested into the water column, again. That's where the ammonia comes from.

and again,nothing that regular water changes can't handle.......

 

[J double R]

water changes shouldnt regulate ammonia. that's what a cycle is for.


fish might be 'adaptable' but our goal as aquarists (mine, at least) is to simulate as natural an environment as possible for the fish. Last i heard, there weren't goldfish in the congo, or the amazon.