Do saltwater fish take up much more bioload than freshwater fish?

[FeatherDuster]

I notice the amount of fish people can place in their saltwater tanks is very small compared to the amount of fish in a freshwater tank. While I understand compatibility portion of the reasoning I was wondering if there is also a bioload reasoning. Do saltwater fish really produce more than 5x the amount of waste compared to freshwater fish? I remember seeing my guppies poop more than my clown fish.

 

[kcress]

Creatures that live in saltwater have to expend more energy to keep the osmotic balance correct. But I'm not sure that's the reason. Seems to me SW fish are also more stoutly built so they actually mass more meat then most FW fish.

But I think the main reason is because marine creatures living in such a massive environment are more susceptible to any rapid shifts. Less fish.. Less rapid excursions.

 

[tamableanimal]

As a general rule size for size I don't believe that sw create much if any more bioload on a tank. Most limit the number of fish to reduce the chance of chemical cycles in the tank. Inso reducing stress levels in the fish. I have seen many fresh water systems that required major cleaning just because of the bio overload. I believe that with the cost of this hobby people tend to be more careful as to how many are added.

 

[wcolwell88]

One of the marine aquarium books I read said that if you only keep one fish per 10 gal., they can usually fight off diseases like ick on their own without needing medication added to the tank which may not be good for your inverts.

 

[dolfans1]

It really isn't the number of fish, but the size of the fish that matters. SW fish in general are larger than FW. I've seen a guideline of 1 inch of fish per 2 gallons of water, but even this is pretty rough. A 5" grouper or puffer will generate more waste than 5 1" chromis.

Also, other critters like many inverts also generate waste (although they clean up waste too). Although they are more "waste neutral," they still add to the bioload and are often unaccounted for when calculating fish stocking levels.

 

[SHK_ATK]

Bioload def has something to do with stocking as saltwater tank (esp nanos) tend to have crashes, Agression def comes to mind when stocking, fish (esp salt) dont behave "normally" when not in the right tank size let alone being in the right one but being overstock. Less fish and more room = less agression (although they are always exeptions to the rule)

 

[zhonk]

If you add up all the fish in the ocean and the all of the water in the oceans, and you do simillar counts for fresh water fish. You will find that each marine fish has much much more water per pound of fish. Because of this fresh waterfish have adapted to higher levels of toxins in the water, while marine fish don't realy need this because of all the space for their waste.

 

[Pufferpunk]

All I have to do on an overstocked FW tank is larger WC. Not as economical on a SW tank.

 

[kay-bee]

I don't think oceanic 'toxins' are evenly distributed (an estruary, for example, is probaby more nutrient heavy than an area of water hundreds of miles from land. For some reason, some SW fish are able to tolerate high toxins (damsels come to mind), even though they're usually found in low nutrient/low toxin reef environments.

Also not all marine fish are larger than their fresh water counter parts. It would interesting to know however, would a 8" grouper have a greater bio-load than a similarly sized cichlid, for example.

In reef set ups, keeping nutrient and 'toxin' levels as low as possible is desired because of the water quality requirements of certain corals, etc. I think the more fish you have the more challenging it would be to maintain that quality.

I have 75gal FW african cichlid tank with over 20 fish in it. Meanwhile my 65gal reef tank contains just 4 small fish (2"-2.5" and they're pretty much maxed out in size). Their small size and associated small dietary requirement translates into a small bioload which makes keeping water quality ideal for my corals. 20 small fish in my 65 SW tank would be deterimental. At least that's how I see it, anyway.

On the other hand, I've got a (in my opinion) overstocked SW Fish Only 45gal tank with 7 fish (2" to 4"). I've been very lax/negligent on water changes (maybe a 35%water change every 2 months; I'm actually overdue for a water change right now, but nitrates are only reading 15ppm as of yesterday). No way I could go that long without a water change in my FW tanks.

 

[zhonk]

It would not be evenly spread, but the fish still don't have to wallow in it. It is spread out, if not evenly.