The Puffer Forum

If the small tank had flow-through water changes (automated) and provided sufficient current for exercise along with refuge for rest/sleep, stunting would be less likely. Clean water of the appropriate type, diet, and exercise all contribute to and are required for normal growth.

I can second the high flow advice... I have about 30x turnover in my 55 gallon, and I'm still looking for ways to increase it. The puffers seem to enjoy swimming in it.... although they do take every opportunity to rest their lazy spotted bums behind rocks!

Jhong - your "enhanced" avatar is a hoot! I love it!

So finally we can sex GSPs.

Thanks! She's just fishing for compliments! ( )

All I need now is a "Hello sailor" caption below it. Sordid little puffer!

before you ask im not pimping out your puffer

I was wondering why FW systems have the 1in/gall rule wheras marine systems require 1in/5gallons ? Is it because the Oxygen concentration is less the more salt you add? and if that is so, would it be like making one of us live on Everest without extra Oxygen tanks?

puffermama wrote:I was wondering why FW systems have the 1in/gall rule wheras marine systems require 1in/5gallons ? Is it because the Oxygen concentration is less the more salt you add? and if that is so, would it be like making one of us live on Everest without extra Oxygen tanks?

Actually, the 1 inch per gallon rule is more a myth than anything. It only applies to small, slim bodied fish like neon tetras. It really is not a good way to determine what and how much of something you can put into a tank.

The reason you have to put less in a salt water tank is for a few reasons. In salt water tanks, levels fluctuate more, and these creatures are more sensitive to change. It takes less ammonia and other chemicals to affect them than most fresh fish. And a lot of critters in saltwater are carnivourous and are messy eaters who requite more water in order to keep levels stable.

Thanks! but that still doesn't answer the availability of O2 question. and a fish would almost certainly be mor sensitive to other fluctuations if it was already struggling to 'breathe'!

As dissolved solids increases, maximum dissolved oxygen decreases.... hence, in saltwater, yes, much less oxygen can be dissolved than in freshwater. This has implications not only for the fish, but also for the filtration.

In addition, to echo what lunarflame posted, saltwater fish can be somewhat more sensitive to chemicals -- for example, nitrates. Inverterbrates -- shrimp, snails, and especially corals, are MUCH more sensitive.

However, the major reason is that the physiology of FW fish is quite different from SW fish... to maintain osmotic pressure (ie the correct level of salts in their bodies), they behave very differently. The upshot of this is that fish in saltwater accumulate a lot more of the ions from the water, and also have to drink large quantities of water constantly. They have to work much harder and are much more dependant on water quality. I can't begin to explain this properly, but this site can: http://www.madsci.org/posts/archives/de ... .Zo.r.html. (look at points 3 & 4).

j

To clarify a bit more, SW fish must drink water to replace the contant water loss from osmosis, and what they drink logically includes all the mineral ions in SW. They have to excrete (via both kidneys and gills) those excess ions. FW have the other side of the same coin, they get water by osmosis constantly, and have to excrete that while saving as many of their needed mineral ions as possible. Brackish water fish situation depends on the density/concentration. At about 1.008 they are in the "neutral' zone, below that their situation is similar to FW fish but milder, above that they are similar to SW fish, but milder until the density appoaches that of full SW.

Oxygen is not the limiting factor in either situation. Maintenance of water quality is almost always the limiting factor. FW fish deal with changing water parameters routinely - wet season/dry season, snow melt season, etc. are a given. Ocean water is remarkably stable over near-geologic time, so the fish have not developed the mechanisms required for adaptation to frequent changes in basic water parameters.

HTH

Ok, let me see if I've got this right.

Being in fresh water is like sitting in a bathtub full of say .. champagne, whereas being in salt water means having to drink the same quantity of the stuff. It is somewhat easier to get drunk in the latter, so the fish have developed good systems to get rid of the alcohol.
But if you replace champagne for say, whiskey, it would do more damage to have ot drink it than to have to sit in it?

Would that be a fairish assessment?

Well, I'm not in the habit of drinking something in which I, or anyone else, is sitting, but that could be a similar idea. But a key point is still that FW fish are accustomed and adapted to some degree of change in water parameters, and SW are far less so, therefore have more issues with shifts. And the hypertonic/hypotonic environment might correspond to whiskey/champagne roughly, but your skin is quite distinct from your respiratory system, while a fish has both in the same medium.

The keys are the relative osmotic pressure with which the fish is surrounded, and the presence or lack thereof with the adaptive changes to the environment.

I think I see, it's not really about the volume of water but more about the relative sensitivities of the fishes living in the two different envirnments. and the fact that larger amounts of water are more stable than lesser ones.

FW fish absorb a lot of stuff through their skin by osmosis, but this is presumably better at keeping harmful substances out than internal linings, if that is the way SW fish in fact replace water which they lose through their skin. Or do SW fish have two way osmosis going on?

I imagine the nice round shape helps Puffers keep the osmotic pressure in better balance than if they had hands and feet. I don't suppose my hands would stop going all pruney even if I drank all the time while standing in the sea.

Osmosis through something as complex as fish skin is very close to RO, only water is moving. Through the gills is different - there is ionic movement as well as water, plus there active transport of ions in both directions in both FW and SW fish. Skin is much simpler, water in when the fish is saltier than the water (FW), water out when the water is saltier than the fish (SW).

In osmosis, water always moves toward the lower concentration of water, not salts/ions.