Fishkeeping Myths And Bad Advice Received

We're interested to hear about the fishkeeping myths you've suffered with and or the bad advice you may have received along the way... hoping to get some funny stories out of this but also be informative for others too!

Here's a few to get things started...

I know one myth it tool me a long time to get over was that nutrients into he water column don't necessarily cause algae, more important is healthy plant growth which will then out compete algae.

Also liquid carbon - not actually liquid carbon, and 10 times less effective as pressurised co2. Also a really dangerous chemical used to sterilize surgical instruments! Useful as an algecide though!

I think one most of us have suffered from is the fish in cycling myth, you can add fish after a week etc. There's loads of great info on this elsewhere in the forum... suffice to say the water doesn't magically prepare itself for fish over a week of being sat there doing nothing! I also remember as a kind cleaning the filter sponge to get rid of poo and sterilizing it with hot water... not realising I was washing away all the good bacteria too!

I also think the usefulness of UV filters is massively over reported. If you don't have green water, there's not much point I don't believe!

Any thoughts or questions on these?

Have you also suffered from myths or bad advice? Bought anything you regret? I know I have...

Myths:

"pH must be altered with chemicals to get it exactly 7.0"
This is not true. No fish in the hobby must have a pH exactly 7.0, some need it lower, some need it higher. And using chemicals in a tank, other than a dechlorinator/water conditioner and plant food if the tank has live plants, is not recommended.


"You can keep bettas in tiny tanks because they live in puddles in the wild"
Not true. In the wild bettas live in shallow, slow moving water covering large areas; a typical betta habitat is a rice paddy. They can survive a dry season in puddles, but many don't make it.


"All fish can be kept in small tanks because they only grow to the size of the tank"
Not true. The body may stop growing in a small tank but it comes with internal problems which significantly shorten the life of the fish. There is still some debate about whether or not the internal organs continue to grow. The tank should always be big enough to accommodate the full adult size of the fish.



Bad advice -

I was once told by a shop that I could keep an angelfish in my new 125 litre tank. Needless to say, I didn't buy one.

I overheard one shop worker telling someone they could add a particular bottled bacteria to a brand new tank and they had to fully stock the tank at the same time for it to work. I googled the product when I got home, and the manufacturer's website said you should only add a few fish at the start, then add fish slowly over a few weeks.
I wonder how many fish from that shop survived if that advice was followed?

Thought I'd resurrect this thread, in part because I thought I'd created a thread about "regret purchases" before but can't find it, and another has identified itself recently.

Earlier this year, I bought Seachem Ammonia Alert.  I glance at this each morning for peace of mind but still test ammonium via my JBL kit pre- water change - but have reduced testing my ammonium regularly during the week due to having the SAA.  Elsewhere, I read of people's adverse experiences with this, and it suddenly struck me that I could test it out, knowing that my tap water contains ammonium due to the chloramine.

True enough - having taken out the SAA and placed it in the tapwater, this looks the 'safe' beige/yellow <0.02 ammonia; however, via the JBL liquid-based test kit, the tapwater shows a not-very-safe 0.2-0.4 ammonium.