by Steve Ward
Spring 1999

Dear Dr. Ghoti,
I have a 29 gallon tank that is leaking. Why? What should I do?

Dear Ina,
This is a good time to buy a new tank; either a smaller tank to move your fish into temporarily or a replacement for the 29 (so that you can use all of the equipment that you already have). Of course you might just get that 55 gallon you’ve been thinking about.

Dear Ossa,

Some fish fry hog the food. The same is true in humans, which is why my younger brothers are both bigger than me. This problem increases geometrically because the larger fish have a larger stomach size. With Oscars the effect is very intense because the amount of food consumed is directly related to the size of the stomach, they being predatory in nature. This effect can be minimized by feeding smaller sizes of food, in which case the consumption of food is less dependent on size of the fish, and more dependent on the rate of consumption (this being relatively equal). Frequent feedings sometimes favor the growth of the larger fish because they can consume more at one feeding. The eye problem is related to this disproportionality. When a fish becomes weak the first part of the body to be targeted is often the eyes. Some species are more susceptible to such attacks than others. Oscars are a good example. The larger fish may find a small fish that has died and pick its eyes, then go on to find a weak fish and try the same maneuver, and eventually progress to the point of biting out the eyes of healthy fish which are smaller than them. As to what you should; I think you should remove any fish that are significantly larger than their siblings, especially if they show a bulging belly in the morning when you know that they haven’t been fed for several hours. In addition you might try the finer grades of food to stave off the size discrepancy.

Dear Brian,
Yes, but there are several species of Artemia (Brine shrimp), all with unique characteristics. There is also a freshwater relative (Eubranchia vernalis) which is native to this region but may be in danger of extinction due to human activities, occasional droughts, and pollution. The difference in color is usually due to the pigments in the algae on which the shrimp feed.

Dear Anna,
The scientific name of this aquatic plant was changed to Anacharis years ago. It is currently on the Noxious Weed list for some reason (I believe because it is a nuisance in Canada). I have heard that there ARE species of Anacharis which are legal to sell. It is common in some of our local waters but is probably illegal to collect, especially for sale. You might consult a local nursery which deals in pond plants.

Dear Cat,
At least the cats have something to do while you’re away. Cats aren’t as good at catching fish as people think. Maybe their water dish doesn’t taste as good. I find it amusing to see a fish bite the tongue of a cat or have a cat fall in a tank. Let them work it out for themselves.

Dear Mark,

I’ve heard people recommend buffing the affected area with some sort of buffing attachment on a drill, and some recommend using toothpaste as a buffing compound. That’s about all I can tell you except to not use Pearl Drops toothpaste because it leaves a rather dull surface. Maybe one of our readers has some better advice. [Editor’s note: Plastics stores sell special compounds and cloths specifically for removing scratches.]

Dear Joyce,

This is partly because popular fish are often raised in large numbers, which increases the possibility of developing new strains. It’s also partly because the fish are popular DUE TO the variety available. And it’s partly because it’s just due to your imagination.

Dear Donna,

Yes, the sculpins, crabs, shrimp, and anemones found in our local tidepools are generally pretty hardy and even tolerate room-temperature water fairly well. It depends on the particular species, however.

Dear Al,

I doubt seriously that the pleco is eating the tetras. More likely he is chewing on fish that have already died. Try to find out what they are dying of.

Dear Hayden,

The first possibility is that the fish have been traumatized recently, by something impacting the tank, people walking by (especially if the tank is near the floor because feet appear to move so quickly and suddenly), or even something like a cat or a slamming door. If you cut down on the feeding you can likely retrain the fish to come out at mealtime.

The second possibility that comes to mind is that the fish are suffering from a deficiency of some mineral or vitamin. This occasionally happens after a large water change since it takes time for the minerals to leech out of the gravel and into the water. I would try adding one of those Wardley mineral blocks. They call them Neutralizer blocks and they contain calcium, magnesium, and vitamin B1 (thiamine).

News

Coelacanths have been found in Indonesia of the island of Manado Tua. These are some of the most primitive fish extant, long thought to be extinct. The only other known population is thought to be found outside Africa’s Comoro Archipelago, 10,000km to the west. Coelacanths have limb-like fins and bear live young which hatch inside the female from eggs as large as a grapefruit. The report of this discovery can be found in the journal NATURE, Sep 24, 98.

Fish Anecdote

Someone asked me recently what my favorite fish was. I was stumped. I’ve kept a lot of different species and many of them are dear to my heart. One of them was a Sculpin (family Cottidae) that I caught in a local stream. This was a freshwater variety although most species of the genus Cottus are found in saltwater. He had a great personality, accentuated by the serpentine spine, which means that they can turn their heads from side to side as other fish cannot. He ate all of my guppies but I forgave him.