These are often caused by poor nutrition, poor breeding and poor water quality. (Ill. 81+82+85) In some cases, there is a bacterial infection caused by poor care of the fish, e.g., with Malawi or Tanganyika Cichlids (in conjunction with so-called Malawi Bloat) (Ill. 81) The first symptom may be a white patch on the skin that later develops into a pit and/or crater (see Ill. 33) Attention: Not to be confused with an ulcer, which occurs with red bloody patches on the skin (see above) Reference is also made to the hole-in-the-head disease or lateral line organ disease in Cichlids. (Ill. 84-88) Parasites (such as Tetrahymena, skin flukes or false fungal infection) may also cause local pits or craters. (Ill. 80+83+84+90) Furthermore, aggression or cannibalism may be responsible for a skin that has been bitten to pieces or for craters. (see Ill. 89) Also frequently occurs with FishMB or disease caused by weakening in old fish. (Ill. 79+82+85+86) Tip: This damage has many possible causes and can only be diagnosed correctly by microscopic examination.