Fish health through proper nutrition

[Paul B]

First of all, fish are not like us. A cold blooded animal is not only different from it's internal temperature, but almost all of it's systems are different from mammals. We as warm blooded creatures can and do eat almost anything organic that we can swallow and most of it will keep us alive. A fish can not for a couple of reasons. Their internal temperature make it very hard to digest solid fats. We on the other hand have almost the same internal temperature as cows so their fat can easily melt in our intestines and we can absorb it. If a fish eats cow fat such as beef heart, much of it remains solid in their intestines and is eliminated.

Fish have no solid fat. I have filleted thousands of fish as I eat them almost every day and you never see solid fat in fish. But a fish is loaded with oil.

Some fish such as menhaden or as we in NY call them, bunker, are harvested just for their oil. Fish such as makeral or bluefish are loaded with oil and a shark can have 20% of it's weight in pure oil.

A fish uses this oil for a couple of things. One is buoyancy. Oil is lighter than water and it offers fish some buoyancy. A fish such as a shark has no swim bladder and contains such a large amount of oil for this reason. Sharks still sink when they are not swimming but they would sink a lot faster without oil.

True bony fish such as we keep in our tanks also have quite a large amount of oil but they also have a swim bladder so they can maintain equilibrium at any depth. The oil supplements the swim bladder but it is not adjustable to the fish as the swim bladder is.
Oil is not just for buoyancy, the swim bladder which is filled with gas could have evolved to keep a fish buoyant but then why do fish have such a large portion of oil?

I feel that oil is crucial to a fish health and also why fish in captivity are so prone to diseases. Diseases we never see in fish in the sea.

This oil can most likely be produced by the fish but I am sure they are much healthier if they eat a diet that is rich in oil. I have come to this conclusion because from many years SCUBA diving I have learned that the thing fish in the sea eat more than anything else is fish. Whole fish.

As I said, whole fish are about 20% oil. And baby fish have an even higher percentage of oil due to their yoke sack. Over 99% of baby fish are eaten in their first days of life, that is a lot of oil.

(Notice the school of fry to the left of the nurse shark. That is what most fish on a reef eat)

A diet like that would kill us, but we are not fish.

I also know from experience that an oily diet keeps a fish in breeding condition, this is the condition they are always in in the sea and almost never in in a tank.

(you can tell a healthy fish by it's vibrant colors, especially if it is a normally drab colored fish such as this gobi)

For some reason, fish in breeding condition hardly, if ever get sick. I know this from experience. My fish usually live long enough to die of old age or an accident. I also don't have a quarantine or hospital tank as I have not needed either for over 20 years.
The first saltwater fish available for sale in the US were blue devils. I started with seven of these fish and although they lived quite nicely, they just did not have the vibrant colors of the wild fish I always saw in the sea. They also did not spawn, that is until I started feeding them worms every day. A few weeks on this diet and one of the blue devils changed. His normally clear fins turned a brilliant blue like the rest of his body. He became a male and started to court the females. They produced eggs every few weeks for seven years.

(Male blue devil over his nest of eggs, Circa 1973)

Many of us feed commercially prepared foods because it is readily available and easy to feed. I use it myself. But this food is almost always lacking in sufficient oil. The reason for this is that oil goes bad. Even if we freeze it. It also smells bad, is sticky and just nasty stuff.

Thats why they now sell it in capsules. As a kid my Mother used to make me take cod liver oil from a spoon. No other thing tastes as gross. But to a fish, it is like going to an ice cream store.

Oil can be offered a few ways. I feed my fish live blackworms every day because worms have a nice portion of oil in them and I found that I can keep my fish breeding if I let them eat a few worms every day. I also hatch brine shrimp every day for the smaller fish and corals. Baby brine a few hours old are also full of oil. I also feed pellets that I first soak in fish oil. I take fish oil myself every day but without the pellets.

Of course the best food would be small whole fish, but whole fish of the size we need are hard to come by. I have spoken to a commercial fish food manufacturer about this but they never got back to me.

This of course is all my theory and I have nothing scientific to back it up except for my 50+ years of fish keeping and the 200 or so hours I have spent underwater with these creatures.

 

[DJ_in_WV]

As a kid my Mother used to make me take cod liver oil from a spoon

lol you told me you were not that old paul. Nice right up

 

[steamer51]

Do you believe that having a breeding pair of clownfish or other small fish helps provide the fish needed in the diet from the larvae or are they too small and infrequent to make a difference? I am planning multiple refugiums to house pairs or harems of small fish as well as feeder shrimp and emerald crabs that will feed into my main display hoping to get the benefit of the zooplankton in the form of baby fish etc. Do you think this will work? Thanks.

 

[soccerbag]

Great writeup Paul. And I agree with you, 50+ years of fish keeping trumps anything anyone else can offer...lol. Quick question, can you let us know what type of worms you feed and where you get them? Just curious as I wouldn't mind adding this to my food rotation if it's financially feasible (and I'm guessing it is very affordable). Thanks again!

 

[Paul B]

Do you believe that having a breeding pair of clownfish or other small fish helps provide the fish needed in the diet from the larvae or are they too small and infrequent to make a difference?

Unfortunate the clowns we keep in tanks are small and the fry are tiny. All of them together would be a tiny snack for one fish. The fry in that picture I posted above are almost 1/4" long because that nurse shark was about 5'. (No the fry are not from the shark)
On a reef the area near the bottom of the rocks is teeming with fry of various sizes. Most of the fish on a reef dip down to snack on some a few times a day. This makes up a large part of their diet. It would not work in a captive envirnment. If we could get tiny fish that would be great. I can get 1/4" makeral but only dried. My fish eat them but they don't really like them as they have the consistancy of wood.

can you let us know what type of worms you feed and where you get them?

I use live blackworms and have used them all of my life. Here in NY they are common in many pet shops. They can be bought on line but I think you need to order a pound. That is a lot of worms and not easy to keep that many alive. They can be frozen but I developed a worm keeper that keps them alive indefinately. They just need to be in shallow, moving fresh water and not go through pumps.
I feed them every day and al the fish get a few. I would not be able to even keep copperband butterflies much less get many of my fish breeding without the worms.
I feel that they are very important and they keep my fish disease free.
They eat other things also like fresh clam and mysis but worms have a good portion of oil in them and it seems to be the right oil.

 

[miyags]

Do you use the omega 3 gel cap fish oil, you get in the vitamin section to soak food?

 

[soccerbag]

Any chance you could post a pic of your worm keeper? Do you just use fresh tap water or RO?

 

[Paul B]

Yes, and I take it myself. You can only use oil on dry food as it will immediately wash off anything wet. Never use it on frozen food. I take about 30 dry sinking pellets and put about five drops of oil on it. After it soaks in for a few hours I store them in a small glass vial to keep out air. I give them to the fish and LPS corals.
I feed this along with the worms and some of my gobies only eat at night so I put some in in the dark.
I make a pin hole in a capsule to squeeze out the oil. Be careful as sometimes it squirts far, and as I said, it is nasty stuff.

 

[Reef lvr]

Cool read!! Thanks for sharing!!

 

[Paul B]

Any chance you could post a pic of your worm keeper? Do you just use fresh tap water or RO?

I use RO water in the thing. The worms are put in the trough, which is a PVC fence post sliced in half. There are some screens in it to help keep the worms from going into the tank, but most of them make it to the tank anyway and I suck them out with a baster. In the tank the water flows into a plastic container that has a screen around the top to help the worms sink and not be washed into the rest of the tank. There is a small powerhead suspended in the tank that pumps water to the far left end of the trough. I added a small carbon container in the trough that the water flows through.
The worms last forever in here but I could not put in a pound. I buy them by the ounce in a pet shop. For a pound it would have to be a lot larger.
The device needs to cycle just like any fish tank before it will hold worms. I have some eggcrate in there to grow bacteria but for the first couple of weeks the worms will not live and become a smelly mess. It takes a while to cycle it then almost no maintenance is necessary as long as you don't clean it too much. I change the water every week or two.
This picture is old and does not show the pump suspended off the bottom. It is important to raise the pump off the bottom because the worms sink and they will go into the pump. It also does not show the carbon or the eggcrate.